Re: [Tutor] another better way to do this ?
I have read all comments and im a little bit confused. About which script are we talkimng about. I have seen a lot. Roelof From: keithw...@gmail.com Date: Sun, 12 Jan 2014 16:43:40 -0500 CC: tutor@python.org Subject: Re: [Tutor] another better way to do this ? On Sun, Jan 12, 2014 at 2:22 PM, Keith Winston keithw...@gmail.com wrote: There's another approach, I think, that's quite easy if order IS important. Alas, there's one further problem with my script, relating to testing multiple sequential letters in product... but I'm not going to say more, I'll leave it as a problem for the OP. It's an easy fix once you understand the issue. -- Keith ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] another better way to do this ?
From: keithw...@gmail.com Date: Mon, 13 Jan 2014 12:56:45 -0500 Subject: Re: [Tutor] another better way to do this ? To: rwob...@hotmail.com CC: tutor@python.org On Mon, Jan 13, 2014 at 1:14 AM, Roelof Wobben rwob...@hotmail.com wrote: I have read all comments and im a little bit confused. About which script are we talkimng about. I have seen a lot. I am talking about the script/approach I posted. Others have posted other scripts. Hopefully you have the capacity, with whatever approach to reading email you have, to go back and look over messages? There is some confusion because your original message specified that order was important, though the examples you gave did not indicate that (in fact, contradicted it). Also, there was never anything specified about repeated letters: what would be the result of fix_machine(letr, letter) (not to be confused with fix_machine(letter, letr), which would definitely be letr). -- Keith Oke, I think you mean this script : def fix_machine(debris, product): index = 0 for letter in product: test = debris.find(letter, index) if test!= -1: index = test else: # Failure return Give me something that's not useless next time. return product # Success ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] another better way to do this ?
Hello,
Here is the whole exercise with examples.
# By Sam the Great from forums
# That freaking superhero has been frequenting Udacity
# as his favorite boss battle fight stage. The 'Udacity'
# banner keeps breaking, and money is being wasted on
# repairs. This time, we need you to proceduralize the
# fixing process by building a machine to automatically
# search through debris and return the 'Udacity' banner
# to the company, and be able to similarly fix other goods.
# Write a Python procedure fix_machine to take 2 string inputs
# and returns the 2nd input string as the output if all of its
# characters can be found in the 1st input string and Give me
# something that's not useless next time. if it's impossible.
# NOTE: # If you are experiencing difficulties taking
# this problem seriously, please refer back to
# Superhero flyby, the prequel, in Problem Set 11.
# TOOLS: # if statement
# while loop
# string operations
# Unit 1 Basics
# BONUS: #
# 5* # If you've graduated from CS101,
# Gold # try solving this in one line.
# Stars! #
def fix_machine(debris, product):
### WRITE YOUR CODE HERE ###
### TEST CASES ###
print Test case 1: , fix_machine('UdaciousUdacitee', 'Udacity') == Give me
something that's not useless next time.
print Test case 2: , fix_machine('buy me dat Unicorn', 'Udacity') == 'Udacity'
print Test case 3: , fix_machine('AEIOU and sometimes y... c', 'Udacity') ==
'Udacity'
print Test case 4: , fix_machine('wsx0-=mttrhix', 't-shirt') == 't-shirt'
Roelof
To: tutor@python.org
From: alan.ga...@btinternet.com
Date: Sun, 12 Jan 2014 00:45:11 +
Subject: Re: [Tutor] another better way to do this ?
On 11/01/14 21:24, Roelof Wobben wrote:
I have two strings a and b
Now I have to check if the characters of b are all in a.
But they do have to be in the same order.
I'm not sure exactly what you mean? Can you give some examples of
data that pass and that fail the criteria?
Your algorithm below might meet one definition of the spec but
its not valid code since it uses return but is not a function.
length = len(b)
start = 1
while start length :
check = a.find (b[start])
if check == -1 :
return False
start = start + 1
return True
Problems I see are:
1) you start testing at b[1] not b[0]
2) you don't check if the letters are in the same sequence in a as in b
3) you probably could tidy it up using a for loop over b rather than
indexing
But according to the site this can be solved in a one-liner.
That depends on the spec.
And have you covered regular expressions? That is probably one
way to do a one-liner...
But just because you can do it in one line doesn't mean you
should. It's better for code to be readable than short.
HTH
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.flickr.com/photos/alangauldphotos
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[Tutor] another better way to do this ?
Hello, I try to learn python by following the audicity page. Now I have the following problem. I have two strings a and b Now I have to check if the characters of b are all in a. But they do have to be in the same order. So I thought about this solution. length = len(b) start = 1 while start length : check = a.find (b[start]) if check == -1 : return False start = start + 1 return True But according to the site this can be solved in a one-liner. So can someone give me pointers how this can be done and if my solution can work. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] why does this not work
Thanks for all the remarks. The problem was indeed a missing . at the end. Roelof To: tutor@python.org From: alan.ga...@btinternet.com Date: Wed, 24 Apr 2013 09:00:36 +0100 Subject: Re: [Tutor] why does this not work On 24/04/13 04:27, frederico Batista wrote: Dave, you clearly don't know codecademy. Please be nice to him. To be fair to Dave he was very polite and showed the OP all the things that were needed to enable the users of this forum to help him. Very few of us are familiar with codeacademy - indeed until this thread I don't think I've come across it before. I certainly didn't know it had its own runtime environment. Also, I recommend the codecademy forums. They have a lot of material about every exercise. Posting in the most specific forum is always best so if the issue is with codeacademy that would be the best place. But I guess it would be hard for the OP to figure out if his problem is with Python or with Codeacademy... Wrong? 1) your message is in html, not text. So the formatting is messy. It could have been worse, so please learn how to make your email program behave. 2) You didn't show your whole program. If this is all you have in the file, then nothing will print because nothing calls your function. 3) You didn't describe your environment, including python version OS. And if Oscar's conjecture is correct, all bets are off because most of us won't be familiar with the strange environment. 4) I can't see how you could possibly get the message: 'It looks like output other than yes/no does not return Sorry, I didn\'t understand you.' And in fact the last part of the message is different than the literal in the program, so you've got a typo besides. Please use cutpaste to show your actual code, your actual output. After reading oscar's comment, my guess is that codeacademy (not Python) is complaining about the period at the end of your last literal string. -- DaveA -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] why does this not work
Im trying to learn python by a course at codeacademy. Now I have this code : def shut_down(s): s = s.lower() if s == yes: return Shutting down... elif s == no : return Shutdown aborted! else: return Sorry, I didn't understand you But when I run it I see this message: It looks like output other than yes/no does not return Sorry, I didn't understand you. So can anyone explain to me what I did wrong. Roelof___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] join question
Hello,
Solved it.
Problem was that I used fileinfo instead of getinfo.
Thanks for the help.
Roelof
Date: Thu, 14 Oct 2010 18:55:50 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] join question
On Thu, Oct 14, 2010 at 6:43 PM, Alan Gauld
wrote:
Roelof Wobben wrote
print ''.join([zf.getinfo('%s.txt' % p).comment for p in zpp])
So I thought that this would be the same :
for p in zpp:
test = zf.getinfo(p).comment
print ''.join(test)
But it seems not to work
Can anyone explain why not ?
Because it's not the same. test in your version is only a single item.
In the original its a list of items. So to write similar code
explicitly you need:
lst = []
for p in zpp:
test = zf.getinfo(p).comment
lst.append(test)
print ''.join(lst)
HTH,
Alan G.
There are two problems. Alan shows the solution to the joining of each
element of the list, but also you need to have the correct argument for
getinfo. In your first example you append .txt to p, but in the loop
example you fail to append it. See my earlier post
--
Joel Goldstick
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[Tutor] urllib problem
Hoi,
I have this programm :
import urllib
import re
f =
urllib.urlopen(http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=6;)
inhoud = f.read()
f.close()
nummer = re.search('[0-9]', inhoud)
volgende = int(nummer.group())
teller = 1
while teller = 3 :
url = http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=; +
str(volgende)
f = urllib.urlopen(url)
inhoud = f.read()
f.close()
nummer = re.search('[0-9]', inhoud)
print nummer is, nummer.group()
volgende = int(nummer.group())
print volgende
teller = teller + 1
but now the url changes but volgende not.
What do I have done wrong ?
Roelof
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Re: [Tutor] urllib problem
From: st...@pearwood.info
To: tutor@python.org
Date: Tue, 12 Oct 2010 23:58:03 +1100
Subject: Re: [Tutor] urllib problem
On Tue, 12 Oct 2010 11:40:17 pm Roelof Wobben wrote:
Hoi,
I have this programm :
import urllib
import re
f =
urllib.urlopen(http://www.pythonchallenge.com/pc/def/linkedlist.php?
nothing=6) inhoud = f.read()
f.close()
nummer = re.search('[0-9]', inhoud)
volgende = int(nummer.group())
teller = 1
while teller = 3 :
url =
http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=; +
str(volgende) f = urllib.urlopen(url)
inhoud = f.read()
f.close()
nummer = re.search('[0-9]', inhoud)
print nummer is, nummer.group()
volgende = int(nummer.group())
print volgende
teller = teller + 1
but now the url changes but volgende not.
What do I have done wrong ?
Each time through the loop, you set volgende to the same result:
nummer = re.search('[0-9]', inhoud)
volgende = int(nummer.group())
Since inhoud never changes, and the search never changes, the search
result never changes, and volgende never changes.
--
Steven D'Aprano
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Hello,
Here is the output when I print every step in the beginning :
inhoud : and the next nothing is 87599
nummer is 8
volgende is 8
and here is the output in the loop :
url is: http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=8
inhoud is and the next nothing is 59212
nummer is 5
2ste run:
url is: http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=5
inhoud is and the next nothing is 51716
nummer is 5
3ste run:
url is: http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=5
inhoud is and the next nothing is 51716
nummer is 5
4ste run:
I see the problem. It only takes the first number of the nothing.
So I have to look how to solve that.
Roelof
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Re: [Tutor] urllib problem
From: st...@pearwood.info
To: tutor@python.org
Date: Wed, 13 Oct 2010 01:51:16 +1100
Subject: Re: [Tutor] urllib problem
On Tue, 12 Oct 2010 11:58:03 pm Steven D'Aprano wrote:
On Tue, 12 Oct 2010 11:40:17 pm Roelof Wobben wrote:
Hoi,
I have this programm :
import urllib
import re
f =
urllib.urlopen(http://www.pythonchallenge.com/pc/def/linkedlist.ph
p? nothing=6) inhoud = f.read()
f.close()
nummer = re.search('[0-9]', inhoud)
volgende = int(nummer.group())
teller = 1
while teller = 3 :
url =
http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=; +
str(volgende) f = urllib.urlopen(url)
inhoud = f.read()
f.close()
nummer = re.search('[0-9]', inhoud)
print nummer is, nummer.group()
volgende = int(nummer.group())
print volgende
teller = teller + 1
but now the url changes but volgende not.
What do I have done wrong ?
Each time through the loop, you set volgende to the same result:
nummer = re.search('[0-9]', inhoud)
volgende = int(nummer.group())
Since inhoud never changes, and the search never changes, the search
result never changes, and volgende never changes.
Wait, sorry, inhoud should change... I missed the line inhoud = f.read()
My mistake, sorry about that. However, I can now see what is going
wrong. Your regular expression only looks for a single digit:
re.search('[0-9]', inhoud)
If you want any number of digits, you need '[0-9]+' instead.
Starting from the first URL:
f = urllib.urlopen(
... http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=6;)
inhoud = f.read()
f.close()
print inhoud
and the next nothing is 87599
but:
nummer = re.search('[0-9]', inhoud)
nummer.group()
'8'
See, you only get the first digit. Then looking up the page with
nothing=8 gives a first digit starting with 5, and then you get stuck
on 5 forever:
urllib.urlopen(
... http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=8;).read()
'and the next nothing is 59212'
urllib.urlopen(
... http://www.pythonchallenge.com/pc/def/linkedlist.php?nothing=5;).read()
'and the next nothing is 51716'
You need to add a + to the regular expression, which means one or more
digits instead of a single digit.
--
Steven D'Aprano
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Hoi Steven,
Finally solved this puzzle.
Now the next one of the 33 puzzles.
Roelof
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[Tutor] pickle problem
Hello, I have this code : import urllib import pickle image = urllib.URLopener() image.retrieve(http://www.pythonchallenge.com/pc/def/peak.html,banner.p; ) plaatje = open(banner.p, rb) plaatje2 = pickle.load(plaatje) But it gives this output : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test2.py, line 7, in module plaatje2 = pickle.load(plaatje) File C:\Python27\lib\pickle.py, line 1378, in load return Unpickler(file).load() File C:\Python27\lib\pickle.py, line 858, in load dispatch[key](self) KeyError: '' What does this mean ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] list of dict question
Hello,
I have this programm :
tournooi = [{'thuis': 'A','uit': B,'thuisscore': 20, 'uitscore':
15},{'thuis': 'C','uit': D,'thuisscore': 80, 'uitscore': 40}]
stand = []
tussen_thuis = {}
tussen_uit = {}
for wedstrijd in tournooi :
if wedstrijd['thuis'] in stand :
print True
else :
tussen_thuis['ploeg'] = wedstrijd['thuis']
tussen_thuis['wedstrijden'] = 1
if wedstrijd['thuisscore'] wedstrijd['uitscore']:
tussen_thuis['punten'] = 2
else:
tussen_thuis['punten'] = 0
tussen_thuis['voor'] = wedstrijd['thuisscore']
tussen_thuis ['tegen'] = wedstrijd['uitscore']
stand.append(tussen_thuis)
if wedstrijd['uit'] in stand :
print True
else :
tussen_uit['ploeg'] = wedstrijd['uit']
tussen_uit['wedstrijden'] = 1
if wedstrijd['thuisscore'] wedstrijd['uitscore']:
tussen_uit['punten'] = 2
else:
tussen_uit['punten'] = 0
tussen_uit['tegen'] = wedstrijd['thuisscore']
tussen_uit ['voor'] = wedstrijd['uitscore']
stand.append(tussen_uit)
It gives this output :
[{'punten': 2, 'tegen': 40, 'wedstrijden': 1, 'voor': 80, 'ploeg': 'C'},
{'punten': 0, 'tegen': 80, 'wedstrijden': 1, 'voor': 40, 'ploeg': 'D'},
{'punten': 2, 'tegen': 40, 'wedstrijden': 1, 'voor': 80, 'ploeg': 'C'},
{'punten': 0, 'tegen': 80, 'wedstrijden': 1, 'voor': 40, 'ploeg': 'D'}]
So the data of A and B are overwriting by C and D.
How can I prevent this ?
Roelof
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Re: [Tutor] list of dict question
To: tutor@python.org
From: alan.ga...@btinternet.com
Date: Fri, 8 Oct 2010 09:02:05 +0100
Subject: Re: [Tutor] list of dict question
Roelof Wobben wrote
I have this programm :
tournooi = [{'thuis': 'A','uit': B,'thuisscore': 20, 'uitscore':
15},{'thuis': 'C','uit': D,'thuisscore': 80, 'uitscore': 40}]
stand = []
tussen_thuis = {}
tussen_uit = {}
Here you create your dictionary objects.
You never create any more dictionary objects so these are the only
ones you have.
for wedstrijd in tournooi :
if wedstrijd['thuis'] in stand :
print True
stand is a list of dictionaries so this will never be True.
else :
tussen_thuis['ploeg'] = wedstrijd['thuis']
tussen_thuis['wedstrijden'] = 1
if wedstrijd['thuisscore'] wedstrijd['uitscore']:
tussen_thuis['punten'] = 2
else:
tussen_thuis['punten'] = 0
tussen_thuis['voor'] = wedstrijd['thuisscore']
tussen_thuis ['tegen'] = wedstrijd['uitscore']
stand.append(tussen_thuis)
Here you append the dictionary into stand
if wedstrijd['uit'] in stand :
print True
But stand is a list with a dictionary inside so this test
cannot be true since wedstrijg['uit'] is not a dictionary.
else :
tussen_uit['ploeg'] = wedstrijd['uit']
tussen_uit['wedstrijden'] = 1
if wedstrijd['thuisscore'] wedstrijd['uitscore']:
tussen_uit['punten'] = 2
else:
tussen_uit['punten'] = 0
tussen_uit['tegen'] = wedstrijd['thuisscore']
tussen_uit ['voor'] = wedstrijd['uitscore']
stand.append(tussen_uit)
Now you append a second dictionary to stand.
On the next iteration you overwrite those two dictionaries
with new values then append them to the list again.
So you wind up with 2 copies of the updated dictionaries.
So the data of A and B are overwriting by C and D.
How can I prevent this ?
You need to create new dictionaries for each iteration of the loop.
Move the dictionary creation lines inside the loop.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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Hello Alan,
Thank you.
Now i can work on a script which can check if a team exist in standen.
Roelof
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[Tutor] FW: list of dict question
From: rwob...@hotmail.com
To: f...@libero.it
Subject: RE: [Tutor] list of dict question
Date: Fri, 8 Oct 2010 14:53:53 +
Date: Fri, 8 Oct 2010 13:40:04 +0200
From: f...@libero.it
To: tutor@python.org
Subject: Re: [Tutor] list of dict question
Il 08/10/2010 10.02, Alan Gauld ha scritto:
Roelof Wobben wrote
I have this programm :
tournooi = [{'thuis': 'A','uit': B,'thuisscore': 20, 'uitscore':
...
for wedstrijd in tournooi :
if wedstrijd['thuis'] in stand :
print True
stand is a list of dictionaries so this will never be True.
...
if wedstrijd['uit'] in stand :
print True
But stand is a list with a dictionary inside so this test
cannot be true since wedstrijg['uit'] is not a dictionary.
I'll say the same another way: you are searching an apple in a container
of baskets, one of which MAY CONTAIN an apple. But you only see baskets,
and none of those can BE an apple!
My two cents: the following might be still new for you, but this is a
way to check if wedstrijd['thuis'] is in stand:
if wedstrijd['thuis'] in [u['ploeg'] for u in stand]
where you build a temporary list of 'ploeg's in stand and check whether
wedstrijd['thuis'] is found there.
...
On the next iteration you overwrite those two dictionaries
with new values then append them to the list again.
So you wind up with 2 copies of the updated dictionaries.
...
This is difficult for me too: why does this happen? Or, more correctly,
why should this happen? How can you save the current contents of a
dictionary in a list, making sure that the saved values won't change if
you update the dict?
You tell Roelof that the dictionary must be created at every loop, but
if so, where goes the elegance of
myDictList.append(UpdateIt(myDict))
???
Francesco (puzzled)
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Hello Franceso,
Thank you for the answer.
Now find ot how i can find the dict which contains a team.
I thinking now of something like this.
teller = 1
For wedstrijd in tournooi :
if wedstrijd['thuis'] != stand ['ploeg'] :
teller = teller + 1
stand[teller]['wedstrijd'] += 1
Could this work ?
Roelof
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[Tutor] data question
Hello, As a test I would write a programm where a user can input game-data like home-team, away-team, home-score, away-score) and makes a ranking of it. And I'm not looking of a OOP solution because im not comfertle with OOP. Now my question is : In which datatype can I put this data in. I thought myself of a dictonary of tuples. Regards, Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] data question
From: rwob...@hotmail.com To: berma...@cfl.rr.com Subject: RE: [Tutor] data question Date: Sat, 2 Oct 2010 13:09:23 + From: berma...@cfl.rr.com To: rwob...@hotmail.com; tutor@python.org Subject: RE: [Tutor] data question Date: Sat, 2 Oct 2010 09:02:41 -0400 -Original Message- From: tutor-bounces+bermanrl=cfl.rr@python.org [mailto:tutor- bounces+bermanrl=cfl.rr@python.org] On Behalf Of Roelof Wobben Sent: Saturday, October 02, 2010 4:35 AM To: tutor@python.org Subject: [Tutor] data question Hello, Now my question is : In which datatype can I put this data in. Perhaps a simple SQLlite database? http://zetcode.com/databases/sqlitetutorial/ Hope this helps, Robert Regards, Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Oke, Oke, there I can save the input data. But I have also need a data model for team, played_games, game_points, made_points and againts_points. So I think it cannot be done without using a class for games and one for ranking. And figuring out how I can store the game-data in a text or database file. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] data question
To: tutor@python.org From: alan.ga...@btinternet.com Date: Sat, 2 Oct 2010 14:10:25 +0100 Subject: Re: [Tutor] data question Roelof Wobben wrote As a test I would write a programm where a user can input game-data like home-team, away-team, home-score, away-score) and makes a ranking of it. In which datatype can I put this data in. I thought myself of a dictonary of tuples. A dictionary would be good for the basic data but I assume there are more than one of these data items? If so what do they represent? How would they be used? We need a bit more information, even some sample datya might help. It could be a list of dictionaries or even a dictionary of dictionaries. Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Alan, What I meant was this: Let's say we have a tournament of 4 teams A,B,C,D They played this games. A - B 20 - 30 C - D 23 - 67 These data must be stored so I can make a module which make a ranking like this : 1) C 1 - 2 76 - 23 2) B 1 - 2 30 - 20 I hope you know what I wan Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] data question
hello, Still one question. Every game is a dictonary/tuple ? Regards, Roelof Date: Sat, 2 Oct 2010 06:24:16 -0700 From: alan.ga...@btinternet.com Subject: Re: [Tutor] data question To: rwob...@hotmail.com OK, So you want a list of games (possibly one per tournament if you need to compare across tournies) where for each game you store: homeTeam, awayTeam and scores. Each game could be represented as either a tuple or a dictionary depending on how you want to extract the data: game['home'] or game[0] The list should probably be a list... :-) Try defining a short sample database in Python then try extracting some values to get a feel for what suits you best. Create the data in a module(easier to edit mistakes/changes) Then use the prompt to import the data module and play around with it. That way it's easy to change from lists to tuples to dictionaries and see what works. Ultimately this may even be best done using a database but that's probably a step too far for you just now. Alan Gauld Author of the Learn To Program website http://www.alan-g.me.uk/ - Original Message From: Roelof Wobben To: alan.ga...@btinternet.com; tutor@python.org Sent: Saturday, 2 October, 2010 14:15:33 Subject: RE: [Tutor] data question To: tutor@python.org From: alan.ga...@btinternet.com Date: Sat, 2 Oct 2010 14:10:25 +0100 Subject: Re: [Tutor] data question Roelof Wobben wrote As a test I would write a programm where a user can input game-data like home-team, away-team, home-score, away-score) and makes a ranking of it. In which datatype can I put this data in. I thought myself of a dictonary of tuples. A dictionary would be good for the basic data but I assume there are more than one of these data items? If so what do they represent? How would they be used? We need a bit more information, even some sample datya might help. It could be a list of dictionaries or even a dictionary of dictionaries. Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Alan, What I meant was this: Let's say we have a tournament of 4 teams A,B,C,D They played this games. A - B 20 - 30 C - D 23 - 67 These data must be stored so I can make a module which make a ranking like this : 1) C 1 - 2 76 - 23 2) B 1 - 2 30 - 20 I hope you know what I wan Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] data question
Hello Alan, I think this is what can work : http://www.daniweb.com/code/snippet216750.html I will try it. Roelof From: rwob...@hotmail.com To: alan.ga...@btinternet.com; tutor@python.org Subject: RE: [Tutor] data question Date: Sat, 2 Oct 2010 13:40:21 + hello, Still one question. Every game is a dictonary/tuple ? Regards, Roelof Date: Sat, 2 Oct 2010 06:24:16 -0700 From: alan.ga...@btinternet.com Subject: Re: [Tutor] data question To: rwob...@hotmail.com OK, So you want a list of games (possibly one per tournament if you need to compare across tournies) where for each game you store: homeTeam, awayTeam and scores. Each game could be represented as either a tuple or a dictionary depending on how you want to extract the data: game['home'] or game[0] The list should probably be a list... :-) Try defining a short sample database in Python then try extracting some values to get a feel for what suits you best. Create the data in a module(easier to edit mistakes/changes) Then use the prompt to import the data module and play around with it. That way it's easy to change from lists to tuples to dictionaries and see what works. Ultimately this may even be best done using a database but that's probably a step too far for you just now. Alan Gauld Author of the Learn To Program website http://www.alan-g.me.uk/ - Original Message From: Roelof Wobben To: alan.ga...@btinternet.com; tutor@python.org Sent: Saturday, 2 October, 2010 14:15:33 Subject: RE: [Tutor] data question To: tutor@python.org From: alan.ga...@btinternet.com Date: Sat, 2 Oct 2010 14:10:25 +0100 Subject: Re: [Tutor] data question Roelof Wobben wrote As a test I would write a programm where a user can input game-data like home-team, away-team, home-score, away-score) and makes a ranking of it. In which datatype can I put this data in. I thought myself of a dictonary of tuples. A dictionary would be good for the basic data but I assume there are more than one of these data items? If so what do they represent? How would they be used? We need a bit more information, even some sample datya might help. It could be a list of dictionaries or even a dictionary of dictionaries. Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Alan, What I meant was this: Let's say we have a tournament of 4 teams A,B,C,D They played this games. A - B 20 - 30 C - D 23 - 67 These data must be stored so I can make a module which make a ranking like this : 1) C 1 - 2 76 - 23 2) B 1 - 2 30 - 20 I hope you know what I wan Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] inheritance problem
To: tutor@python.org From: alan.ga...@btinternet.com Date: Fri, 1 Oct 2010 00:59:06 +0100 Subject: Re: [Tutor] inheritance problem Roelof Wobben wrote So i have this programm now : class Deck: def __init__(self): self.cards = [] for suit in range(4): for rank in range(1, 14): self.cards.append(Card(suit, rank)) def deal(self, hands, num_cards=999): num_hands = len(hands) for i in range(num_cards): if self.is_empty(): break # break if out of cards card = self.pop() # take the top card hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand def shuffle(self): import random num_cards = len(self.cards) for i in range(num_cards): j = random.randrange(i, num_cards) self.cards[i], self.cards[j] = self.cards[j], self.cards[i] def remove(self, card): if card in self.cards: self.cards.remove(card) return True else: return False def is_empty(self): return (len(self.cards) == 0) But now Im getting this error message: Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 126, in game.deck.deal([hand], 13) File C:\Users\wobben\workspace\oefeningen\src\test.py, line 24, in deal card = self.pop() # take the top card AttributeError: Deck instance has no attribute 'pop' What went wrong here. The error tells you what is wrong, the Deck has no attribute called pop. Can you see a pop anywhere? I only see a pop here : card = self.pop() # take the top card but no function called pop. So if the code you copied has an error how should it assign a card? I assigned a card by this code : def deal(self, hands, num_cards=999): num_hands = len(hands) for i in range(num_cards): if self.is_empty(): break # break if out of cards card = self.pop() # take the top card hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand Where are the cards stored? How would you get the first card from the collection? Does that work? The cards are stored in a directory named cards. The hands are stored in a directory named hands Think about what the error is telling you and think about how you would fix it. If you don't understand what the error is saying then tell us and we can explain it, but in this case its pretty clearly stated and is one you have seen before. The error is telling me that the function pop does not exist for a directory, So solution is to find out which object contains pop and then change the code. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] inheritance problem
From: rwob...@hotmail.com To: alan.ga...@btinternet.com; tutor@python.org Date: Fri, 1 Oct 2010 06:19:29 + Subject: Re: [Tutor] inheritance problem To: tutor@python.org From: alan.ga...@btinternet.com Date: Fri, 1 Oct 2010 00:59:06 +0100 Subject: Re: [Tutor] inheritance problem Roelof Wobben wrote So i have this programm now : class Deck: def __init__(self): self.cards = [] for suit in range(4): for rank in range(1, 14): self.cards.append(Card(suit, rank)) def deal(self, hands, num_cards=999): num_hands = len(hands) for i in range(num_cards): if self.is_empty(): break # break if out of cards card = self.pop() # take the top card hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand def shuffle(self): import random num_cards = len(self.cards) for i in range(num_cards): j = random.randrange(i, num_cards) self.cards[i], self.cards[j] = self.cards[j], self.cards[i] def remove(self, card): if card in self.cards: self.cards.remove(card) return True else: return False def is_empty(self): return (len(self.cards) == 0) But now Im getting this error message: Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 126, in game.deck.deal([hand], 13) File C:\Users\wobben\workspace\oefeningen\src\test.py, line 24, in deal card = self.pop() # take the top card AttributeError: Deck instance has no attribute 'pop' What went wrong here. The error tells you what is wrong, the Deck has no attribute called pop. Can you see a pop anywhere? I only see a pop here : card = self.pop() # take the top card but no function called pop. So if the code you copied has an error how should it assign a card? I assigned a card by this code : def deal(self, hands, num_cards=999): num_hands = len(hands) for i in range(num_cards): if self.is_empty(): break # break if out of cards card = self.pop() # take the top card hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand Where are the cards stored? How would you get the first card from the collection? Does that work? The cards are stored in a directory named cards. The hands are stored in a directory named hands Think about what the error is telling you and think about how you would fix it. If you don't understand what the error is saying then tell us and we can explain it, but in this case its pretty clearly stated and is one you have seen before. The error is telling me that the function pop does not exist for a directory, So solution is to find out which object contains pop and then change the code. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello, I make a big mistake. Both card and hands are lists and pop can be used on a list. So as Joel said in this rule card = self.pop() there is no list named so I think it must be self.hands.pop() Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] inheritance problem
I assigned a card by this code : def deal(self, hands, num_cards=999): num_hands = len(hands) for i in range(num_cards): if self.is_empty(): break # break if out of cards card = self.pop() # take the top card hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand No this code assigns several HANDS not just cards. The code that assigns a card is inside this function, but you need to narrow it down to the specific lines assigning the card. Oke, The lines that assign card is : hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand The first one takes care to who a card is assigned and the second one assigned it to that person. Where are the cards stored? How would you get the first card from the collection? Does that work? The cards are stored in a directory named cards. Correct. So how do you get a card from the collection stored in self.cards? This is not correct. Card is a list and not a directory. See this : self.cards = [] I make a big mistake. Both card and hands are lists and pop can be used on a list. That's not a mistake, lists are objects too. oke, but I confused two objects and that is a mistake. So as Joel said in this rule card = self.pop() there is no list named so I think it must be self.hands.pop() If you want to assign a card and cards are stored in self.cards why would you use self.hands.pop()? Surely it should be self.cards.pop()? It is. I know that because self.hands is not working. Now Im busy to make this difficult exercise of writing print_hands() But thanks for the time and explantion. OOP is difficult to understand I find. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] inheritance problem
hello, Im following this page : http://openbookproject.net/thinkcs/python/english2e/ch17.html So i have this programm now : class Card: suits = [Clubs, Diamonds, Hearts, Spades] ranks = [narf, Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King] def __init__(self, suit=0, rank=0): self.suit = suit self.rank = rank def __str__(self): return (self.ranks[self.rank] + of + self.suits[self.suit]) class Deck: def __init__(self): self.cards = [] for suit in range(4): for rank in range(1, 14): self.cards.append(Card(suit, rank)) def deal(self, hands, num_cards=999): num_hands = len(hands) for i in range(num_cards): if self.is_empty(): break # break if out of cards card = self.pop() # take the top card hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand def shuffle(self): import random num_cards = len(self.cards) for i in range(num_cards): j = random.randrange(i, num_cards) self.cards[i], self.cards[j] = self.cards[j], self.cards[i] def remove(self, card): if card in self.cards: self.cards.remove(card) return True else: return False def is_empty(self): return (len(self.cards) == 0) class Hand(Deck): def __init__(self, name=): self.cards = [] self.name = name def add(self,card): self.cards.append(card) def deal(self, hands, num_cards=999): num_hands = len(hands) for i in range(num_cards): if self.is_empty(): break # break if out of cards card = self.pop() # take the top card hand = hands[i % num_hands] # whose turn is next? hand.add(card) # add the card to the hand class CardGame: def __init__(self): self.deck = Deck() self.deck.shuffle() class OldMaidHand(Hand): def remove_matches(self): count = 0 original_cards = self.cards[:] for card in original_cards: match = Card(3 - card.suit, card.rank) if match in self.cards: self.cards.remove(card) self.cards.remove(match) print Hand %s: %s matches %s % (self.name, card, match) count = count + 1 return count class OldMaidGame(CardGame): def play(self, names): # remove Queen of Clubs self.deck.remove(Card(0,12)) # make a hand for each player self.hands = [] for name in names: self.hands.append(OldMaidHand(name)) # deal the cards self.deck.deal(self.hands) print -- Cards have been dealt self.printHands() # remove initial matches matches = self.removeAllMatches() print -- Matches discarded, play begins self.printHands() # play until all 50 cards are matched turn = 0 numHands = len(self.hands) while matches 25: matches = matches + self.playOneTurn(turn) turn = (turn + 1) % numHands print -- Game is Over self.printHands() def remove_all_matches(self): count = 0 for hand in self.hands: count = count + hand.remove_matches() return count def find_neighbor(self, i): numHands = len(self.hands) for next in range(1,numHands): neighbor = (i + next) % numHands if not self.hands[neighbor].is_empty(): return neighbor game = CardGame() hand = OldMaidHand(frank) deck = Deck() game.deck.deal([hand], 13) OldMaidHand.print_hands() But now Im getting this error message: Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 126, in module game.deck.deal([hand], 13) File C:\Users\wobben\workspace\oefeningen\src\test.py, line 24, in deal card = self.pop() # take the top card AttributeError: Deck instance has no attribute 'pop' What went wrong here. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] question
Hello, Im now studying this page : http://openbookproject.net/thinkcs/python/english2e/ch16.html But I don't get it why aces are now lower then deuces in the cmp function. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] question
From: rwob...@hotmail.com To: da...@ieee.org Subject: RE: [Tutor] question Date: Tue, 28 Sep 2010 14:22:17 + Date: Tue, 28 Sep 2010 10:02:27 -0400 From: da...@ieee.org To: rwob...@hotmail.com CC: tutor@python.org Subject: Re: [Tutor] question On 2:59 PM, Roelof Wobben wrote: Hello, Im now studying this page : http://openbookproject.net/thinkcs/python/english2e/ch16.html But I don't get it why aces are now lower then deuces in the cmp function. Roelof Why would you be surprised that aces are lower than deuces? If aces are represented by 1, and deuces by 2, then 1 is less than 2. Notice that because self.suit is compared first, an ace of spades is higher than a deuce of hearts. It's only within the same suit that an ace is less than a deuce. DaveA Hello Dave, In some games in the Netherlands Aces can have a value of 11 or 1 . So if Aces are 11 then Deuces is lesser then Aces. Can I say that the position of the list is a representation of the value. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] question
From: rwob...@hotmail.com To: da...@ieee.org Subject: RE: [Tutor] question Date: Tue, 28 Sep 2010 19:14:29 + Date: Tue, 28 Sep 2010 10:49:28 -0400 From: da...@ieee.org To: rwob...@hotmail.com; tutor@python.org Subject: Re: [Tutor] question On 9/28/2010 10:22 AM, Roelof Wobben wrote: Date: Tue, 28 Sep 2010 10:02:27 -0400 From: da...@ieee.org To: rwob...@hotmail.com CC: tutor@python.org Subject: Re: [Tutor] question On 2:59 PM, Roelof Wobben wrote: Hello, Im now studying this page : http://openbookproject.net/thinkcs/python/english2e/ch16.html But I don't get it why aces are now lower then deuces in the cmp function. Roelof Why would you be surprised that aces are lower than deuces? If aces are represented by 1, and deuces by 2, then 1 is less than 2. Notice that because self.suit is compared first, an ace of spades is higher than a deuce of hearts. It's only within the same suit that an ace is less than a deuce. DaveA Hello Dave, In some games in the Netherlands Aces can have a value of 11 or 1 . So if Aces are 11 then Deuces is lesser then Aces. Can I say that the position of the list is a representation of the value. Roelof The class attribute was assigned as follows: ranks = [narf, Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King] So Ace is at position 1. And if you want an Ace, you'd have to supply a 1 to the constructor. I would certainly agree that in many games this wouldn't be the desired case. Some games specify aces higher than kings, some have no ordering among face cards, some let the player choose. If the Card class needed to cover all cases, then one might need to make the __cmp__() method parameterizable, so that at different times, the cards might sort differently. But this is one implementation of the Card class, and hopefully it's self-consistent in the course. DaveA Oke, Thanks. Then now figuring out how to solve this problem : Modify __cmp__ so that Aces are ranked higher than Kings So aces with value 1 must be higher then Kings with 11 I think I have to make another rule in the rank part like this If self.rank = Aces and self.rank = Kings then return -1 or 1 Tomorrrow I will investigate this. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class method problem
Hello, Fine that you are in a arque But can we come back to my problem. How can I take care that test2 can be initialized. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] class method problem
Hello, I have this code: class zoeken() : pass def __len__(self): return 0 def __str__(self): return test2 def find(self, strng, ch, start, stop): index = start while index len(strng) and index stop: if strng[index] == ch: return index index += 1 return -1 test = zoeken() test.woord = tamara test2 = zoeken.find(test, a, 1,5) print test(test2) But now I get this message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 20, in module test2 = zoeken.find(test, a, 1,5) TypeError: find() takes exactly 5 arguments (4 given) I can do zoeken.find (test2,test, a, 1,5) but then I get this message: Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 20, in module zoeken.find( test2, test, a, 1,5) NameError: name 'test2' is not defined Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] class method problem
Hello, Still the same errors Roelof Date: Sat, 25 Sep 2010 19:33:52 +0100 Subject: Re: [Tutor] class method problem From: andre...@gmail.com To: rwob...@hotmail.com Your method receives 4 arguments and you didn't define one default. Try to do something like this: def find(self, strng=None, ch=None, start=None, stop=None): Or any other default values that matches your needs. On 25 September 2010 19:15, Roelof Wobben wrote: Hello, I have this code: class zoeken() : á ápass á ádef __len__(self): á á á áreturn 0 á ádef __str__(self): á á á áreturn test2 á ádef find(self, strng, ch, start, stop): á á á áindex = start á á á áwhile index len(strng) and index stop: á á á á á áif strng[index] == ch: á á á á á á á áreturn index á á á á á áindex += 1 á á á á á áreturn -1 test = zoeken() test.woord = tamara test2 = zoeken.find(test, a, 1,5) print test(test2) But now I get this message : Traceback (most recent call last): áFile C:\Users\wobben\workspace\oefeningen\src\test.py, line 20, in á átest2 = zoeken.find(test, a, 1,5) TypeError: find() takes exactly 5 arguments (4 given) I can do zoeken.find (test2,test, a, 1,5) but then I get this message: Traceback (most recent call last): áFile C:\Users\wobben\workspace\oefeningen\src\test.py, line 20, in á ázoeken.find( test2, test, a, 1,5) NameError: name 'test2' is not defined Roelof ___ Tutor maillist á- átu...@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor -- Andreh Palma ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] pure function problem
Date: Fri, 24 Sep 2010 06:29:03 -0400 From: da...@ieee.org To: rwob...@hotmail.com CC: tutor@python.org Subject: Re: [Tutor] pure function problem On 2:59 PM, Roelof Wobben wrote: From: st...@pearwood.info On Fri, 24 Sep 2010 06:20:25 am Roelof Wobben wrote: time =ijd() [...] print time(uitkomst) Why are you calling time as a function, when it is a tijd instance? Hello Steve, I found this in my tutorial. 13.8. Instances as return values¶ Functions can return instances. For example, find_center takes a Rectangle as an argument and returns a Point that contains the coordinates of the center of the Rectangle: def find_center(box): p =oint() p.x =ox.corner.x + box.width/2.0 p.y =ox.corner.y - box.height/2.0 return p To call this function, pass box as an argument and assign the result to a variable: center =ind_center(box) print_point(center) (50.0, 100.0) So i followed it but appearently not the good way. Roelof There's a big difference between print_point() and print time(). print_point() in your tutorial is a function, presumably defined someplace else. You used print time(), (no underscore), which uses the print statement, and tries to call a function called time(). Since you defined time as an instance of your class, and didn't do anything special, it's not callable. DaveA Oke, I see it now. I have to us a function that i had to write a few questions before. Thanks everybody Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] pure function problem
Hello, I have to rewrite a function to a pure function. So i have this : class tijd : pass def increment(time, seconds): sum = tijd() sum.seconds = time.seconds + seconds if sum.seconds 60 : minutes, seconds = divmod(sum.seconds, 60) sum.seconds = seconds sum.minutes = time.minutes + minutes return sum time = tijd() time.hour = 20 time.minutes = 20 time.seconds = 20 seconds = 20 uitkomst = tijd() uitkomst = increment(time, seconds) print uitkomst.minutes, uitkomst.seconds But now I get this error message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 22, in module print uitkomst.minutes, uitkomst.seconds AttributeError: tijd instance has no attribute 'minutes' So it looks like uitkomst has no attribute minutes but uitkomst is a instance of tijd which has a attribute minutes. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] pure function problem
Date: Thu, 23 Sep 2010 05:36:58 -0400 Subject: Re: [Tutor] pure function problem From: jemejo...@gmail.com To: tutor@python.org CC: rwob...@hotmail.com The problem is that your class definition doesn't do anything to explicitly set those attributes. On Thu, Sep 23, 2010 at 4:58 AM, Roelof Wobben rwob...@hotmail.com wrote: snip class tijd : pass You're not doing any explicit setting of attributes at the class level. snip time = tijd() time.hour = 20 time.minutes = 20 time.seconds = 20 You set them on this instance. seconds = 20 uitkomst = tijd() But not on this one. What you probably want to do is something like this: class tijd(object): def __init__(self): self.hour = 20 self.minutes = 20 self.seconds = 20 Or if you prefer to set these when you create the instance, you can pass in values like this: class tijd(object): def __init__(self, hour=20, minutes=20, seconds=20): self.hour = hour self.minutes = minutes self.seconds = seconds I noticed something odd just a sec ago. You have this: uitkomst = tijd() uitkomst = increment(time, seconds) print uitkomst.minutes, uitkomst.seconds You're creating a tijd instance, binding uitkomst to it, then overwriting that instance with what you return from increment(). Anyway, hth. - jmj Correct, I try to find a way to solve this error message. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] pure function problem
From: rwob...@hotmail.com To: tutor@python.org Subject: RE: [Tutor] pure function problem Date: Thu, 23 Sep 2010 10:15:07 + Date: Thu, 23 Sep 2010 05:36:58 -0400 Subject: Re: [Tutor] pure function problem From: jemejo...@gmail.com To: tutor@python.org CC: rwob...@hotmail.com The problem is that your class definition doesn't do anything to explicitly set those attributes. On Thu, Sep 23, 2010 at 4:58 AM, Roelof Wobben wrote: class tijd : pass You're not doing any explicit setting of attributes at the class level. time = tijd() time.hour = 20 time.minutes = 20 time.seconds = 20 You set them on this instance. seconds = 20 uitkomst = tijd() But not on this one. What you probably want to do is something like this: class tijd(object): def __init__(self): self.hour = 20 self.minutes = 20 self.seconds = 20 Or if you prefer to set these when you create the instance, you can pass in values like this: class tijd(object): def __init__(self, hour=20, minutes=20, seconds=20): self.hour = hour self.minutes = minutes self.seconds = seconds I noticed something odd just a sec ago. You have this: uitkomst = tijd() uitkomst = increment(time, seconds) print uitkomst.minutes, uitkomst.seconds You're creating a tijd instance, binding uitkomst to it, then overwriting that instance with what you return from increment(). Anyway, hth. - jmj Correct, I try to find a way to solve this error message. Roelof Oke, I changed everything to this : class tijd : pass def increment(time, seconds): sum = tijd() sum.seconds = time.seconds + seconds if sum.seconds 60 : minutes, seconds = divmod(sum.seconds, 60) sum.seconds = seconds sum.minutes = time.minutes + minutes return sum time = tijd() time.hour = 20 time.minutes = 20 time.seconds = 20 seconds = 20 uitkomst = increment(time, seconds) print time(uitkomst) But now Im getting this error message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 21, in module print time(uitkomst) AttributeError: tijd instance has no __call__ method Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] pure function problem
From: st...@pearwood.info To: tutor@python.org Date: Fri, 24 Sep 2010 13:00:40 +1000 Subject: Re: [Tutor] pure function problem Roelof, please learn to delete unnecessarily quoted text. There's no need to quoted the entire discussion every time you answer. On Fri, 24 Sep 2010 06:20:25 am Roelof Wobben wrote: time = tijd() [...] print time(uitkomst) Why are you calling time as a function, when it is a tijd instance? -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Steve, I found this in my tutorial. 13.8. Instances as return values¶ Functions can return instances. For example, find_center takes a Rectangle as an argument and returns a Point that contains the coordinates of the center of the Rectangle: def find_center(box): p = Point() p.x = box.corner.x + box.width/2.0 p.y = box.corner.y - box.height/2.0 return p To call this function, pass box as an argument and assign the result to a variable: center = find_center(box) print_point(center) (50.0, 100.0) So i followed it but appearently not the good way. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] class function problem
HEllo, I have this exercise : 3.Rewrite the increment function so that it doesn’t contain any loops. The increment function looks like this : def increment(time, seconds): time.seconds = time.seconds + seconds while time.seconds= 60: time.seconds = time.seconds - 60 time.minutes = time.minutes + 1 while time.minutes= 60: time.minutes = time.minutes - 60 time.hours = time.hours + 1 So I thought that recursion can do the job. So I wrote this : class tijd : pass def incrememt_seconds(time): time.seconds = time.seconds - 60 time.minutes = time.minutes + 1 if time.seconds= 60 : increment_seconds(time,seconds, minutes) return time def increment_minutes(time): time.minutes = time.minutes - 60 time.hours = time.hours + 1 if time.minutes= 60 : increment_minutes(time, minutes,hours) return time def increment(time, seconds): time.seconds = time.seconds + seconds if time.seconds= 60 : increment_seconds(time) if time.minutes= 60 : increment_minutes(time) return time time = tijd() time.hour = 20 time.minutes = 20 time.seconds = 20 seconds = 20 uitkomst = increment(time, seconds) But how can i Check the outcome. print uitkomst gives the object and print time(uitkomst) gives this error message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 34, in module print time(uitkomst) AttributeError: tijd instance has no __call__ method Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] class function problem
From: hugo.yo...@gmail.com Date: Wed, 22 Sep 2010 16:16:45 +0200 Subject: Re: [Tutor] class function problem To: rwob...@hotmail.com CC: tutor@python.org On Wed, Sep 22, 2010 at 9:10 AM, Roelof Wobben wrote: HEllo, I have this exercise : 3.Rewrite the increment function so that it doesn’t contain any loops. The increment function looks like this : def increment(time, seconds): time.seconds = time.seconds + seconds while time.seconds= 60: time.seconds = time.seconds - 60 time.minutes = time.minutes + 1 while time.minutes= 60: time.minutes = time.minutes - 60 time.hours = time.hours + 1 So I thought that recursion can do the job. That's very clever. But you might argue that recursion is technically still a loop, albeit an implicit one. There is a simpler way to do this, without loops entirely. Hint: repeated subtraction while your number is greater than some constant, what you are doing, is essentially the same as doing one division operation. Sorry. I don't get it. When I have 62 seconds that's 1 minutes and 2 seconds. I have no clue how I can this with a division. But how can i Check the outcome. print uitkomst gives the object and print time(uitkomst) gives this error message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 34, in print time(uitkomst) AttributeError: tijd instance has no __call__ method You can do print uitkomst.seconds, uitkomst.minutes, uitkomst.hours. Alternatively, write a suitable __str__ method for your tijd class. Then you can just do print uitkomst Roelof Oke, thanks for the tip. Stupid I could thought that myself. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Can this be done easly
Hello, I have this programm : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(Point): def _init_(self, width=0, length=0): self.width = width self.length = length punt = Point(3,4) rechthoek = Rectangle (punt,20,30) Now I wonder how I can change this to rechthoek = rectangle (punt,20,20) This one gives as error message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 12, in module rechthoek = Rectangle (punt,20,30) TypeError: __init__() takes at most 3 arguments (4 given) Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Can this be done easly
Date: Sun, 19 Sep 2010 14:19:46 +0200 From: knack...@googlemail.com To: tutor@python.org Subject: Re: [Tutor] Can this be done easly Am 19.09.2010 10:49, schrieb Roelof Wobben: Hello, I have this programm : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(Point): def _init_(self, width=0, length=0): self.width = width self.length = length You're inheriting the Point Class, but you don't initialise it. For some detailled description of inheritance in Python I rather suggest to check out some tutorials instead of trying to explain it. Also, others on this list can do this probably better. Here's one reference: http://diveintopython.org/object_oriented_framework/index.html But now some remarks regarding your problem: First, I would not consider a Rectangle as a special Point. It's not a relation like a Sportscar is a Car (is-a-relationship). It's more a relation a Rectangle has 4 Points (has-a-relationship), or 1 Point and a width and length. So, it's probably better to express your Rectangle class like this: class Rectangle(object): def __init__(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length then you go (with German names ;-)): punkt = Point(3,4) rechteck = Rectangle(punkt,20,30) In your Rectangle class, the __init__ method takes only two arguments (not counting the instance: self), but you're passing three arguments. At the beginning, the error messages are a bit confusing, because they count the instance as one of the arguments. So it tells you, that you have given 4 arguments, but you might wonder Hey, I gave you 3. HTH, Jan punt = Point(3,4) rechthoek = Rectangle (punt,20,30) Now I wonder how I can change this to rechthoek = rectangle (punt,20,20) This one gives as error message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 12, in rechthoek = Rectangle (punt,20,30) TypeError: __init__() takes at most 3 arguments (4 given) Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello, When I change everything to this : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(object): def _init_(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length punt = Point(3,4) rechthoek = Rectangle (punt,20,30) I get this message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 13, in module rechthoek = Rectangle (punt,20,30) TypeError: object.__new__() takes no parameters Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Can this be done easly
To: tutor@python.org From: __pete...@web.de Date: Sun, 19 Sep 2010 18:04:25 +0200 Subject: Re: [Tutor] Can this be done easly Roelof Wobben wrote: When I change everything to this : I get this message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 13, in rechthoek = Rectangle (punt,20,30) TypeError: object.__new__() takes no parameters Hint: why does this work: def __init__(self, x=0, y=0): ...while this doesnt: def _init_(self, base_point, width=0, length=0): Peter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hoi, Maybe because base_point has no value ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] FW: Can this be done easly
From: rwob...@hotmail.com To: __pete...@web.de Subject: RE: [Tutor] Can this be done easly Date: Sun, 19 Sep 2010 17:01:22 + To: tutor@python.org From: __pete...@web.de Date: Sun, 19 Sep 2010 18:27:54 +0200 Subject: Re: [Tutor] Can this be done easly Roelof Wobben wrote: Hint: why does this work: def __init__(self, x=0, y=0): ...while this doesnt: def _init_(self, base_point, width=0, length=0): Peter Maybe because base_point has no value ? No. One __init__ has two underscores (correct) on each side, the other _init_ only one (wrong). ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello, Everybody thanks. For this exercise : 3.Write a function named move_rect that takes a Rectangle and two parameters named dx and dy. It should change the location of the rectangle by adding dx to the x coordinate of corner and adding dy to the y coordinate of corner. Is this one of the possible solutions : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(object): def __init__(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length def moverect(rectangle, dx, dy): rechthoek.base_point.y += dy rechthoek.base_point.x +=dx return rechthoek punt = Point(3,4) rechthoek = Rectangle (punt,20,30) test = moverect (Rectangle, 4,3) print rechthoek.base_point.x Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] FW: Can this be done easly
To: tutor@python.org From: __pete...@web.de Date: Sun, 19 Sep 2010 20:07:05 +0200 Subject: Re: [Tutor] FW: Can this be done easly Roelof Wobben wrote: For this exercise : 3.Write a function named move_rect that takes a Rectangle and two parameters named dx and dy. It should change the location of the rectangle by adding dx to the x coordinate of corner and adding dy to the y coordinate of corner. Is this one of the possible solutions : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(object): def __init__(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length def moverect(rectangle, dx, dy): rechthoek.base_point.y += dy rechthoek.base_point.x +=dx return rechthoek punt = Point(3,4) rechthoek = Rectangle (punt,20,30) test = moverect (Rectangle, 4,3) print rechthoek.base_point.x At first glance I'd say so. At second glance I see that you pass the class and not an instance to the moverect() routine. Your program only seems to work because you are not using the parameter rectangle but the global rechthoek variable and as soon as you are trying to move rectangles with a different variable name everything will break. If I were to run your program I might even find more errors or problematic behaviours. In the long run it's not a sustainable model to verify the correctness of your programs by asking someone on the internet who is just as likely to be wrong as you or might even fool you. Instead add some tests. For example, you could precalculate the expected position and then check if the new position meets your expectation: r = Rectangle(Point(3, 4), 20, 30) moverect(r, 10, 11) if r.base_point.x == 13 and r.base_point.y == 15: print looks good else: print needs work Because tests are needed very often there are libraries accompanying the interpreter (unittest, doctest) to formalize them and for simple runtime checks there is the assert statement. Instead of the if...else you could write assert r.base_point.x == 13, wrong x position %d % r.base_point.x assert r.base_point.y == 15, wrong y position %d % r.base_point.y Peter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello, I changed the programm to this : import unittest class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(object): def __init__(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length def moverect(roelof, dx, dy): roelof.base_point.y += dy roelof.base_point.x +=dx return roelof r = Rectangle(Point(3, 4), 20, 30) moverect(r, 10, 11) assert r.base_point.x == 13, wrong x position %d % r.base_point.x assert r.base_point.y == 15, wrong y position %d % r.base_point.y But no output at all Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] FW: Can this be done easly
From: andreeng...@gmail.com Date: Sun, 19 Sep 2010 20:54:01 +0200 Subject: Re: [Tutor] FW: Can this be done easly To: rwob...@hotmail.com CC: tutor@python.org On Sun, Sep 19, 2010 at 8:33 PM, Roelof Wobben wrote: Hello, I changed the programm to this : import unittest class Point: def __init__(self, x=0, y=0): self.x = x self.y = y class Rectangle(object): def __init__(self, base_point, width=0, length=0): self.base_point = base_point self.width = width self.length = length def moverect(roelof, dx, dy): roelof.base_point.y += dy roelof.base_point.x +=dx return roelof r = Rectangle(Point(3, 4), 20, 30) moverect(r, 10, 11) assert r.base_point.x == 13, wrong x position %d % r.base_point.x assert r.base_point.y == 15, wrong y position %d % r.base_point.y But no output at all Which output had you expected, and why? -- André Engels, andreeng...@gmail.com Hello, Oke, I see it now. There is only output when it's not right. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] class problem
Hello, I have this exercise : Create and print a Point object, and then use id to print the object’s unique identifier. Translate the hexadecimal form into decimal and confirm that they match. So I thought that this would solve it: class Point: def __init__(self, x=0, y=0): self.x = x self.y = y P=(Point) a=0 b=0 a=id(P) print a print b print P But now id is a decimal so I don't can't translate it. Did I something wrong ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] FW: class problem
Hello , Thanks everyone. I solved it by this : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y P=Point() print P print id(P) and a calculator which can convert hex to decimal. Roelof From: st...@pearwood.info To: tutor@python.org Date: Sun, 19 Sep 2010 01:54:11 +1000 Subject: Re: [Tutor] class problem On Sat, 18 Sep 2010 07:14:03 pm Roelof Wobben wrote: P=(Point) This line does not do what you think it does. Brackets in Python are used for two things, grouping and calling functions. To call a function, or a class, you need to have the brackets *after* the function: P = Point() # what about arguments to the function? If you surround it with brackets, as you do above, it does nothing. It's like this: x = (1+1) # exactly the same as x = 1+1 without brackets a=0 b=0 a=id(P) It is a waste of time to initialise variables immediately before initialising them again. print a print b print P But now id is a decimal so I don't can't translate it. id(x) returns an integer. By default, integers always print in decimal, if you want to print them in hex you can do this: hex(id(P)) -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] next class problem
Hello, I have this exercise : Rewrite the distance function from chapter 5 so that it takes two Points as parameters instead of four numbers. I have this solution : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y def distance(p1,p2): dx = p2.x - p1.x dy = p2.y - p1.y dsquared = dx**2 + dy**2 result = dsquared**0.5 return result P1 = Point() P1.x = 3 P1.y = 3 P2 = Point() P2.x = 6 P2.y = 7 result = distance (P1,P2) print result Is this the correct solution ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] next class problem
Date: Sat, 18 Sep 2010 13:40:55 -0400 From: bgai...@gmail.com To: rwob...@hotmail.com CC: tutor@python.org Subject: Re: [Tutor] next class problem On 9/18/2010 1:20 PM, Roelof Wobben wrote: Hello, I have this exercise : Rewrite the distance function from chapter 5 so that it takes two Points as parameters instead of four numbers. I have this solution : class Point: def __init__(self, x=0, y=0): self.x = x self.y = y def distance(p1,p2): dx = p2.x - p1.x dy = p2.y - p1.y dsquared = dx**2 + dy**2 result = dsquared**0.5 return result P1 = Point() P1.x = 3 P1.y = 3 P2 = Point() P2.x = 6 P2.y = 7 result = distance (P1,P2) print result Is this the correct solution ? What is your criteria for correct? There is no one correct solution! You seem to be passing 2 points, as requested. Do you get the correct answer? Then it mus be correct. FWIW Python convention recommends names starting with lower case except for classes and constants. Therefore p1 and p2 are preferred to P1 and P2. Also why not initialize x and y thus: p1 = Point(3,3) That is what the __init__ is for. -- Bob Gailer 919-636-4239 Chapel Hill NC Hello, Thank you. Learned another thing. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] robots question
Hello,
I changed a lot because of your suggestions.
But one thing is still a puzzle.
The robots don't move anymore.
What I have is this :
#
# robots.py
#
from gasp import *
SCREEN_WIDTH = 640
SCREEN_HEIGHT = 480
GRID_WIDTH = SCREEN_WIDTH/10 - 1
GRID_HEIGHT = SCREEN_HEIGHT/10 - 1
def place_player():
# x = random.randint(0, GRID_WIDTH)
# y = random.randint(0, GRID_HEIGHT)
x, y = GRID_WIDTH/2 + 3, GRID_HEIGHT/2
return {'shape': Circle((10*x+5, 10*y+5), 5, filled=True), 'x': x, 'y': y}
def place_robot(x, y, junk=False):
return {'shape': Box((10*x, 10*y), 10, 10, filled = junk), 'x': x, 'y': y}
def place_robots(numbots):
robots=[]
# for i in range(numbots):
#x = random.randint(0, GRID_WIDTH)
#y = random.randint(0, GRID_HEIGHT)
#robots.append(place_robot(x, y))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 + 2, junk =
False))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 - 2, junk =
False))
return robots
def move_player(player):
update_when('key_pressed')
if key_pressed('escape'):
return True
elif key_pressed('4'):
if player['x'] 0: player['x'] -= 1
elif key_pressed('7'):
if player['x'] 0: player['x'] -= 1
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('8'):
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('9'):
if player['x'] GRID_WIDTH: player['x'] += 1
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('6'):
if player['x'] GRID_WIDTH: player['x'] += 1
elif key_pressed('3'):
if player['x'] GRID_WIDTH: player['x'] += 1
if player['y'] 0: player['y'] -= 1
elif key_pressed('2'):
if player['y'] 0: player['y'] -= 1
elif key_pressed('1'):
if player['x'] 0: player['x'] -= 1
if player['y'] 0: player['y'] -= 1
elif key_pressed('0'):
player['x'] = random.randint(0, GRID_WIDTH)
player['y'] = random.randint(0, GRID_HEIGHT)
else:
return False
move_to(player['shape'], (10*player['x']+5, 10*player['y']+5))
return False
def collided(thing1, thing2):
return thing1['x'] == thing2['x'] and thing1['y'] == thing2['y']
def check_collisions(robots, junk, player):
# check whether player has collided with anything
for thing in robots + junk:
if collided(thing, player):
return True
return False
def move_robot(robot, player):
if robot['x'] player['x']: robot['x'] += 1
elif robot['x'] player['x']: robot['x'] -= 1
if robot['y'] player['y']: robot['y'] += 1
elif robot['y'] player['y']: robot['y'] -= 1
move_to(robot['shape'], (10*robot['x'], 10*robot['y']))
def move_robots(robots, player):
for robot in robots:
move_robot(robot, player)
def play_game():
begin_graphics(SCREEN_WIDTH, SCREEN_HEIGHT)
player = place_player()
robots = []
place_robots(4)
junk = [ place_robot(GRID_WIDTH/2, GRID_HEIGHT/2, junk=True )]
defeated = False
while not defeated:
quit = move_player(player)
if quit:
break
move_robots(robots, player)
defeated = check_collisions(robots, junk, player)
if defeated:
remove_from_screen(player['shape'])
for thing in robots + junk:
remove_from_screen(thing['shape'])
Text(They got you!, (240, 240), size=32)
sleep(3)
end_graphics()
if __name__ == '__main__':
play_game()
Roelof
To: tutor@python.org
From: alan.ga...@btinternet.com
Date: Fri, 17 Sep 2010 01:14:32 +0100
Subject: Re: [Tutor] robots question
Roelof Wobben rwob...@hotmail.com wrote
#
# robots.py
This is pretty weird code, there are several odd things in it.
def place_player():
# x = random.randint(0, GRID_WIDTH)
# y = random.randint(0, GRID_HEIGHT)
x, y = GRID_WIDTH/2 + 3, GRID_HEIGHT/2
return {'shape': Circle((10*x+5, 10*y+5), 5, filled=True), 'x': x,
'y': y}
So this returns a dictionary which always contains the same data.
def place_robot(x,y, junk):
x = random.randint(0, GRID_WIDTH)
y = random.randint(0, GRID_HEIGHT)
return {'shape': Box((10*x, 10*y), 10, 10), 'x': x, 'y': y}
This returns a similar dict but with random data.
It ignores the values of x and y passed in and does not use junk at
all.
def place_robots(numbots):
robots = []
# for i in range(numbots):
#x = random.randint(0, GRID_WIDTH)
#y = random.randint(0, GRID_HEIGHT)
#robots.append(place_robot(x, y))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 + 2,
junk= False))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 - 2,
junk = False))
print type(robots)
return robots
This returns a list of 2 dictionaries. The x,y parameters are ignored
by the function.
def move_player(player):
update_when
[Tutor] robots question
Hello,
As a exercise from this book ( Thinking like a computer scientist ) I have to
make this programm on this
page(http://openbookproject.net/thinkcs/python/english2e/ch12.html)
Exercise 11
#
# robots.py
#
from gasp import *
SCREEN_WIDTH = 640
SCREEN_HEIGHT = 480
GRID_WIDTH = SCREEN_WIDTH/10 - 1
GRID_HEIGHT = SCREEN_HEIGHT/10 - 1
def place_player():
# x = random.randint(0, GRID_WIDTH)
# y = random.randint(0, GRID_HEIGHT)
x, y = GRID_WIDTH/2 + 3, GRID_HEIGHT/2
return {'shape': Circle((10*x+5, 10*y+5), 5, filled=True), 'x': x, 'y': y}
def place_robot(x,y, junk):
x = random.randint(0, GRID_WIDTH)
y = random.randint(0, GRID_HEIGHT)
return {'shape': Box((10*x, 10*y), 10, 10), 'x': x, 'y': y}
def place_robots(numbots):
robots = []
# for i in range(numbots):
#x = random.randint(0, GRID_WIDTH)
#y = random.randint(0, GRID_HEIGHT)
#robots.append(place_robot(x, y))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 + 2, junk= False))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 - 2, junk =
False))
return robots
def move_player(player):
update_when('key_pressed')
if key_pressed('escape'):
return True
elif key_pressed('4'):
if player['x'] 0: player['x'] -= 1
elif key_pressed('7'):
if player['x'] 0: player['x'] -= 1
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('8'):
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('9'):
if player['x'] GRID_WIDTH: player['x'] += 1
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('6'):
if player['x'] GRID_WIDTH: player['x'] += 1
elif key_pressed('3'):
if player['x'] GRID_WIDTH: player['x'] += 1
if player['y'] 0: player['y'] -= 1
elif key_pressed('2'):
if player['y'] 0: player['y'] -= 1
elif key_pressed('1'):
if player['x'] 0: player['x'] -= 1
if player['y'] 0: player['y'] -= 1
elif key_pressed('0'):
player['x'] = random.randint(0, GRID_WIDTH)
player['y'] = random.randint(0, GRID_HEIGHT)
else:
return False
move_to(player['shape'], (10*player['x']+5, 10*player['y']+5))
return False
def collided(thing1, thing2):
return thing1['x'] == thing2['x'] and thing1['y'] == thing2['y']
def check_collisions(robots, junk, player):
# check whether player has collided with anything
for thing in robots + junk:
if collided(thing, player):
return True
return False
def move_robot(robot, player):
if robot['x'] player['x']: robot['x'] += 1
elif robot['x'] player['x']: robot['x'] -= 1
if robot['y'] player['y']: robot['y'] += 1
elif robot['y'] player['y']: robot['y'] -= 1
move_to(robot['shape'], (10*robot['x'], 10*robot['y']))
def move_robots(robots, player):
for robot in robots:
move_robot(robot, player)
def play_game(robots):
begin_graphics(SCREEN_WIDTH, SCREEN_HEIGHT)
player = place_player()
robot = place_robots(4)
junk = [place_robot(GRID_WIDTH/2, GRID_HEIGHT/2, junk=true )]
defeated = False
while not defeated:
quit = move_player(player)
if quit:
break
move_robots(robot, player)
defeated = check_collisions(robot, player, junk)
if defeated:
remove_from_screen(player['shape'])
for thing in robots + junk:
remove_from_screen(thing['shape'])
Text(They got you!, (240, 240), size=32)
sleep(3)
end_graphics()
if __name__ == '__main__':
play_game(2)
But now Im getting this error message :
Traceback (most recent call last):
File /root/workspace/test2/src/test.py, line 120, in module
play_game(2)
File /root/workspace/test2/src/test.py, line 106, in play_game
defeated = check_collisions(robot, player, junk)
File /root/workspace/test2/src/test.py, line 73, in check_collisions
for thing in robots + junk:
TypeError: can only concatenate list (not dict) to list
I understand that robots is a dict and junk is a list.
Is that right ?
And why does the book say that when this message is appearing.
Roelof
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[Tutor] FW: robots question
From: rwob...@hotmail.com
To: __pete...@web.de
Subject: RE: [Tutor] robots question
Date: Thu, 16 Sep 2010 17:43:41 +
Hello ,
I change everything to this :
#
# robots.py
#
from gasp import *
SCREEN_WIDTH = 640
SCREEN_HEIGHT = 480
GRID_WIDTH = SCREEN_WIDTH/10 - 1
GRID_HEIGHT = SCREEN_HEIGHT/10 - 1
def place_player():
# x = random.randint(0, GRID_WIDTH)
# y = random.randint(0, GRID_HEIGHT)
x, y = GRID_WIDTH/2 + 3, GRID_HEIGHT/2
return {'shape': Circle((10*x+5, 10*y+5), 5, filled=True), 'x': x, 'y': y}
def place_robot(x,y, junk):
x = random.randint(0, GRID_WIDTH)
y = random.randint(0, GRID_HEIGHT)
return {'shape': Box((10*x, 10*y), 10, 10), 'x': x, 'y': y}
def place_robots(numbots):
robots = []
# for i in range(numbots):
#x = random.randint(0, GRID_WIDTH)
#y = random.randint(0, GRID_HEIGHT)
#robots.append(place_robot(x, y))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 + 2, junk= False))
robots.append(place_robot(GRID_WIDTH/2 - 4, GRID_HEIGHT/2 - 2, junk =
False))
print type(robots)
return robots
def move_player(player):
update_when('key_pressed')
if key_pressed('escape'):
return True
elif key_pressed('4'):
if player['x'] 0: player['x'] -= 1
elif key_pressed('7'):
if player['x'] 0: player['x'] -= 1
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('8'):
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('9'):
if player['x'] GRID_WIDTH: player['x'] += 1
if player['y'] GRID_HEIGHT: player['y'] += 1
elif key_pressed('6'):
if player['x'] GRID_WIDTH: player['x'] += 1
elif key_pressed('3'):
if player['x'] GRID_WIDTH: player['x'] += 1
if player['y'] 0: player['y'] -= 1
elif key_pressed('2'):
if player['y'] 0: player['y'] -= 1
elif key_pressed('1'):
if player['x'] 0: player['x'] -= 1
if player['y'] 0: player['y'] -= 1
elif key_pressed('0'):
player['x'] = random.randint(0, GRID_WIDTH)
player['y'] = random.randint(0, GRID_HEIGHT)
else:
return False
move_to(player['shape'], (10*player['x']+5, 10*player['y']+5))
return False
def collided(thing1, thing2):
return thing1['x'] == thing2['x'] and thing1['y'] == thing2['y']
def check_collisions(robots, junk, player):
# check whether player has collided with anything
for thing in robots + junk:
if collided(thing, player):
return True
return False
def move_robot(robot, player):
if robot['x'] player['x']: robot['x'] += 1
elif robot['x'] player['x']: robot['x'] -= 1
if robot['y'] player['y']: robot['y'] += 1
elif robot['y'] player['y']: robot['y'] -= 1
move_to(robot['shape'], (10*robot['x'], 10*robot['y']))
def move_robots(robots, player):
for robot in robots:
move_robot(robot, player)
def play_game():
begin_graphics(SCREEN_WIDTH, SCREEN_HEIGHT)
player = place_player()
robot = place_robots(4)
junk = [ place_robot(GRID_WIDTH/2, GRID_HEIGHT/2, junk=true )]
robots = []
defeated = False
while not defeated:
quit = move_player(player)
if quit:
break
move_robots(robots, player)
print type robots, type(robots)
print type junk, type(junk)
print type player, type(player)
defeated = check_collisions(robots, player, junk)
if defeated:
remove_from_screen(player['shape'])
for thing in robots + junk:
remove_from_screen(thing['shape'])
Text(They got you!, (240, 240), size=32)
sleep(3)
end_graphics()
if __name__ == '__main__':
play_game()
And now Im getting this message :
** Message: pygobject_register_sinkfunc is deprecated (GtkWindow)
** Message: pygobject_register_sinkfunc is deprecated (GtkInvisible)
** Message: pygobject_register_sinkfunc is deprecated (GtkObject)
type 'list'
type robotsTraceback (most recent call last):
type 'list'
type junk type 'list'
type player type 'dict'
File /root/workspace/test2/src/test.py, line 125, in module
play_game()
File /root/workspace/test2/src/test.py, line 111, in play_game
defeated = check_collisions(robots, player, junk)
File /root/workspace/test2/src/test.py, line 74, in check_collisions
for thing in robots + junk:
TypeError: can only concatenate list (not dict) to list
So far I can see the problem is that player is a dict and the rest is a list.
Is this the correct conclusion ?
Roelof
To: tutor@python.org
From: __pete...@web.de
Date: Thu, 16 Sep 2010 18:10:13 +0200
Subject: Re: [Tutor] robots question
Roelof Wobben wrote:
As a exercise from this book ( Thinking like a computer scientist ) I have
to make this programm on this
page(http://openbookproject.net/thinkcs/python/english2e/ch12.html)
Exercise 11
def check_collisions(robots, junk
[Tutor] FW: FW: robots question
From: rwob...@hotmail.com To: __pete...@web.de Subject: RE: [Tutor] FW: robots question Date: Thu, 16 Sep 2010 18:22:03 + To: tutor@python.org From: __pete...@web.de Date: Thu, 16 Sep 2010 20:10:02 +0200 Subject: Re: [Tutor] FW: robots question Roelof Wobben wrote: I change everything to this : def check_collisions(robots, junk, player): defeated = check_collisions(robots, player, junk) Do you see the problem? yes, Player en junk are swapped. print type robots, type(robots) print type junk, type(junk) print type player, type(player) Adding print statements for debugging purposes is a good approach. And now Im getting this message : ** Message: pygobject_register_sinkfunc is deprecated (GtkWindow) ** Message: pygobject_register_sinkfunc is deprecated (GtkInvisible) ** Message: pygobject_register_sinkfunc is deprecated (GtkObject) type robotsTraceback (most recent call last): type junk type player File /root/workspace/test2/src/test.py, line 125, in play_game() File /root/workspace/test2/src/test.py, line 111, in play_game defeated = check_collisions(robots, player, junk) File /root/workspace/test2/src/test.py, line 74, in check_collisions for thing in robots + junk: TypeError: can only concatenate list (not dict) to list So far I can see the problem is that player is a dict and the rest is a list. Is this the correct conclusion ? It may be correct but it's a low-level view. A more appropriate description would be that you are trying to concatenate a list of robots with a player. Oke, I will try to make one list which will contain the robots and a player. Peter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] FW: wierd replace problem
Date: Tue, 14 Sep 2010 22:15:40 +0100
From: wpr...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] FW: wierd replace problem
On 14 September 2010 21:10, Roelof Wobben
wrote:
I understand it but I try to understand why in a file there is this
'word python makes a 'word.
Python doesn't change what it reads from the file. However, depending
on how you ask Python to tell you what it's read (or what the contents
of a string variable is), it might display it quoted, and/or include
escape charaters, or not as the case may be. If what you've read from
the file contains quotes, then obviously you need to be careful to not
mistake Python's quoting of the value of a string as being *part* of
that string. Neither must you mistake the escape character (if
applicable) from being actually part of the string.
For example, consider the following exchange in the Python shell
(please try all of this yourself and experiment):
s = 'blah'
s
'blah'
print s
blah
I assign the value of 'blah' to the string s. So far simple enough.
Obviosuly the quotes used int the assignment of the string does not
form part of the string itself. Their utility is only to delineate to
Python the start of the string, and the end of the string.
In the next line I ask Python to evaluate the expression s, which it
duly reporst as 'blah'. Again, it's using normal Python convention to
format the data as a string, because that's what s is, a string
object. But the quotes are formatting, they're not really part of the
string.
In the next line I ask Python to print s. Now, the true content of s
is printed as it is, and hence you can see that the quotes are not part
of the string.
Now consider the following exchange in the Python shell where I open a
file and write some text to it to prove this point:
f = open('test.txt', 'w+')
f.write('blah')
f.close()
import os
os.system('notepad test.txt')
The last line above opens the text file test.txt in Notepad so you can
see the contents. As you can see, no quotes or anything else. Now,
while open, suppose we put a single quote in the file, so it reads:
'blah
...and suppose we then save it and exit notepad so you're back in the
Python shell. Then we do:
f=open('test.txt','r+')
s=f.read()
f.close()
s
'blah
Now I've read the contents of the file back into a string variable s,
and asked Python to evaluate (output) this string object.
Notice, Python is now formatting the string with *doube* quotes
(previously it defaulted to single quotes) to avoid having to escape
the single quote that forms part of the string. If Python had used
single quotes instead, then there would've been an ambiguity with the
single quote that's part of the string and so it would've had to escape
that too. So consequently it formats the string with double quotes,
which is valid Python syntax and avoids the backslash. (Stating the
obvious, strings can be quoted with double or single quotes.) As
before, the double quotes, as with the single quotes earlier, are not
part of the string. They are merely formatting since Python is being
asked to display a string and hence it must indicate the start and end
of the string with suitable quote characters.
Now, as before do:
print s
'blah
As before, with print you see the contents of the string as it is (and
as indeed it is also in the file that you saved). Just the single quote
you added at the front of Blah. No double or single quotes or anything
else.
Now finally, let's try something a bit more elaborate. Do again:
os.system('notepad test.txt')
Then put into the file the following 2 lines of text (notice the file
now contains 2 lines, and both single and double quotes...):
++This line is double quoted in the file and the quotes have +
symbols around them.++
---'---This line is single quoted in the file and the quotes have -
symbols around them.---'---
Save it, exit Notepad, then do:
f=open('test.txt', 'r+')
s=f.read()
f.close()
s
'++This line is double quoted in the file and the quotes have +
symbols around them.++\n---\'---This line is single quoted in the
file and the quotes have - symbols around them.---\'---\n'
print s
++This line is double quoted in the file and the quotes have +
symbols around them.++
---'---This line is single quoted in the file and the quotes have -
symbols around them.---'---
Notice we read both lines in the file into one single string. See how
Python formats that as a string object, and escapes not only the single
quotes but also the line break characters (\n). See also when Python
is asked to print the string, you can see the escape characters
really there. See what's happened? Do you understand why?
Walter
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[Tutor] FW: wierd replace problem
Hello,
Strip (''') does not work.
Still this message : SyntaxError: EOL while scanning string literal
So I think I go for the suggestion of Bob en develop a programm which deletes
all the ' and by scanning it character by character.
Roelof
From: st...@pearwood.info
To: tutor@python.org
Date: Tue, 14 Sep 2010 09:39:29 +1000
Subject: Re: [Tutor] wierd replace problem
On Tue, 14 Sep 2010 09:08:24 am Joel Goldstick wrote:
On Mon, Sep 13, 2010 at 6:41 PM, Steven D'Aprano
wrote:
On Tue, 14 Sep 2010 04:18:36 am Joel Goldstick wrote:
How about using str.split() to put words in a list, then run
strip() over each word with the required characters to be removed
('`)
Doesn't work. strip() only removes characters at the beginning and
end of the word, not in the middle:
Exactly, you first split the words into a list of words, then strip
each word
Of course, if you don't want to remove ALL punctuation marks, but only
those at the beginning and end of words, then strip() is a reasonable
approach. But if the aim is to strip out all punctuation, no matter
where, then it can't work.
Since the aim is to count words, a better approach might be a hybrid --
remove all punctuation marks like commas, fullstops, etc. no matter
where they appear, keep internal apostrophes so that words like can't
are different from cant, but remove external ones. Although that
loses information in the case of (e.g.) dialect speech:
'e said 'e were going to kill the lady, Mister Holmes!
cried the lad excitedly.
You probably want to count the word as 'e rather than just e.
And hyphenation is tricky to. A lone hyphen - like these - should be
deleted. But double-dashes--like these--are word separators, so need to
be replaced by a space. Otherwise, single hyphens should be kept. If a
word begins or ends with a hyphen, it should be be joined up with the
previous or next word. But then it gets more complicated, because you
don't know whether to keep the hyphen after joining or not.
E.g. if the line ends with:
blah blah blah blah some-
thing blah blah blah.
should the joined up word become the compound word some-thing or the
regular word something? In general, there's no way to be sure,
although you can make a good guess by looking it up in a dictionary and
assuming that regular words should be preferred to compound words. But
that will fail if the word has changed over time, such as cooperate,
which until very recently used to be written co-operate, and before
that as coöperate.
--
Steven D'Aprano
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Re: [Tutor] FW: wierd replace problem
Date: Tue, 14 Sep 2010 09:32:38 +0200
From: timomli...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] FW: wierd replace problem
On 14-09-10 09:28, Roelof Wobben wrote:
Hello,
Strip (''') does not work.
Still this message : SyntaxError: EOL while scanning string literal
Review it again, see how many quotes you are using.
For example, this won't work either:
s = 'foo'bar'
You need to escape the quotes with a backslash, like:
s = 'foo\'bar'
print s
foo'bar
Cheers,
Timo
Hello Timo,
I understand what you mean but we're talking about a text-file which will be
read in a string.
So I can't escape the quotes. As far as I know I can't control how Python is
reading a text-file with quotes.
Roelof
So I think I go for the suggestion of Bob en develop a programm which
deletes all the ' and by scanning it character by character.
Roelof
From: st...@pearwood.info
To: tutor@python.org
Date: Tue, 14 Sep 2010 09:39:29 +1000
Subject: Re: [Tutor] wierd replace problem
On Tue, 14 Sep 2010 09:08:24 am Joel Goldstick wrote:
On Mon, Sep 13, 2010 at 6:41 PM, Steven D'Aprano
wrote:
On Tue, 14 Sep 2010 04:18:36 am Joel Goldstick wrote:
How about using str.split() to put words in a list, then run
strip() over each word with the required characters to be removed
('`)
Doesn't work. strip() only removes characters at the beginning and
end of the word, not in the middle:
Exactly, you first split the words into a list of words, then strip
each word
Of course, if you don't want to remove ALL punctuation marks, but only
those at the beginning and end of words, then strip() is a reasonable
approach. But if the aim is to strip out all punctuation, no matter
where, then it can't work.
Since the aim is to count words, a better approach might be a hybrid --
remove all punctuation marks like commas, fullstops, etc. no matter
where they appear, keep internal apostrophes so that words like can't
are different from cant, but remove external ones. Although that
loses information in the case of (e.g.) dialect speech:
'e said 'e were going to kill the lady, Mister Holmes!
cried the lad excitedly.
You probably want to count the word as 'e rather than just e.
And hyphenation is tricky to. A lone hyphen - like these - should be
deleted. But double-dashes--like these--are word separators, so need to
be replaced by a space. Otherwise, single hyphens should be kept. If a
word begins or ends with a hyphen, it should be be joined up with the
previous or next word. But then it gets more complicated, because you
don't know whether to keep the hyphen after joining or not.
E.g. if the line ends with:
blah blah blah blah some-
thing blah blah blah.
should the joined up word become the compound word some-thing or the
regular word something? In general, there's no way to be sure,
although you can make a good guess by looking it up in a dictionary and
assuming that regular words should be preferred to compound words. But
that will fail if the word has changed over time, such as cooperate,
which until very recently used to be written co-operate, and before
that as coöperate.
--
Steven D'Aprano
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Re: [Tutor] FW: wierd replace problem
Oke, Can this also be the same problem. In the text is this : 'tis is represent as 'this And this part is represent as part. Roelof Date: Tue, 14 Sep 2010 11:41:28 +0100 From: wpr...@gmail.com To: tutor@python.org Subject: Re: [Tutor] FW: wierd replace problem On 14 September 2010 11:09, James Mills wrote: $ python Python 2.6.5 (r265:79063, Jun 13 2010, 14:03:16) [GCC 4.4.4 (CRUX)] on linux2 Type help, copyright, credits or license for more information. s = foo\bar' s 'foobar\'' I'd like to point something out here. Typing s as James showed here at the prompt outputs a version of the string that Python will understand if fed again, consequently it's encoded to do the same escaping of characters as you would have to do if you put that expression into your python source yourself. If however you entered: print s ... then Python would've print the value of s as it really is, withou any escape characters or anything else, e.g.: print s foobar' So, even though you see a \' in the output posted by James above, the \ that was output by Python isn't actually part of the string (e.g. it's not really there as such), it was only output that way by Python to disambiguate the value of the string. So, at the risk of belaboring this point to death, if you do: s = '\'\'\'' then the contents of the string s in memory is ''' The string does not contain the slashes. The slashes are only there to help you make Python understand that the quotes must not be interpreted as the end of the string, but rather as part of the string. You could get the exact same result by doing: s = ''' Here there's no ambiguity and consequently no need for slashes since the string is delineated by double quotes and not single quotes. Hope that helps. Walter ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] FW: wierd replace problem
From: st...@pearwood.info
To: tutor@python.org
Date: Tue, 14 Sep 2010 21:30:01 +1000
Subject: Re: [Tutor] FW: wierd replace problem
On Tue, 14 Sep 2010 05:38:18 pm Roelof Wobben wrote:
Strip (''') does not work.
Still this message : SyntaxError: EOL while scanning string
literal
[...]
I understand what you mean but we're talking about a text-file which
will be read in a string. So I can't escape the quotes. As far as I
know I can't control how Python is reading a text-file with quotes.
The text file has nothing to do with this. The text file is fine. The
error is in the strings that YOU type, not the text file.
Strings must have MATCHING quotation marks:
This is okay: abcd
So is this: 'abcd'
But this is not: abcd'
You need to *look carefully* at strings you type and make sure that the
start and end quotes match. Likewise you can't insert the SAME
quotation mark in a string unless you escape it first:
This is okay: 'Hello,' he said.
So is this: 'Goodbye, she replied.'
But this is not: 'He said I can't see you.'
But this is okay: 'He said I can\'t see you.'
--
Steven D'Aprano
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Oke,
I see the problem.
When I have this sentence : `'Tis so,' said the Duchess: `and the moral of
that is--Oh,
'tis love, 'tis love, that makes the world go round!'
And I do string.strip() the output will be :
`'This and that one does not fit your explanation.
So I have to strip everything before I strip it.
Roelof
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Re: [Tutor] FW: wierd replace problem
From: rwob...@hotmail.com
To: joel.goldst...@gmail.com
Subject: RE: [Tutor] FW: wierd replace problem
Date: Tue, 14 Sep 2010 15:43:42 +
Date: Tue, 14 Sep 2010 11:28:10 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] FW: wierd replace problem
On Tue, Sep 14, 2010 at 10:29 AM, Roelof Wobben
wrote:
I offer my solution. I didn't bother to make every word lower case,
and I think that would improve the result
Please offer critique, improvements
Some explaination:
line 5 -- I read the complete text into full_text, while first
replacing -- with a space
line 7 -- I split the full text string into words
lines 8 - 15 -- Word by word I strip all sorts of characters that
aren't in words from the front and back of each 'word'
lines 11 - 14 -- this is EAFP -- try to add one to the bin with that
word, if no such bin, make it and give it 1
lines 16, 17 -- since dicts don't sort, sort on the keys then loop thru
the keys to print out the key (word) and the count
1 #! /usr/bin/env python
2
3 word_count = {}
4 file = open ('alice_in_wonderland.txt', 'r')
5 full_text = file.read().replace('--',' ')
6
7 full_text_words = full_text.split()
8 for words in full_text_words:
9 stripped_words = words.strip(.,!?'`\- ();:)
10 ##print stripped_words
11 try:
12 word_count[stripped_words] += 1
13 except KeyError:
14 word_count[stripped_words] = 1
15
16 ordered_keys = word_count.keys()
17 ordered_keys.sort()
18 ##print ordered_keys
19 print All the words and their frequency in 'alice in wonderland'
20 for k in ordered_keys:
21 print k, word_count[k]
22
--
Joel Goldstick
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Hello Joel,
Your solution works.
Im getting grazy. I tried it two days with strip and get a eof error message
and now no messages.
Roelof
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Re: [Tutor] FW: wierd replace problem
Date: Tue, 14 Sep 2010 17:45:35 +0200
From: f...@libero.it
To: tutor@python.org
Subject: Re: [Tutor] FW: wierd replace problem
On 14/09/2010 16.29, Roelof Wobben wrote:
...
Oke,
I see the problem.
When I have this sentence : `'Tis so,' said the Duchess: `and the moral of
that is--Oh,
'tis love, 'tis love, that makes the world go round!'
And I do string.strip() the output will be :
`'This and that one does not fit your explanation.
So I have to strip everything before I strip it.
After some trial and error with the interpreter, I found this:
st = `'Tis so,' said the Duchess: `and the moral of that is--Oh,
'tis love, 'tis love, that makes the world go round!' # notice the
starting and ending triple quotes, just to avoid all the backslashes and
the ambiguities with quoting characters ;-)
wordlist = [thisone.strip(',!` :-) for thisone in st.replace('',
).replace(-, ).split()]
I don't know if you read the chapter regarding list comprehensions in
your tutorial, but this is one of those. First of all, I replace all
double quotes and dashes - with spaces:
st.replace('', ).replace(-, )
then I use split() to divide the long string in a list of almost-words.
At the end, with the for clause in the list comprehension, I strip all
leading and trailing non-letters (again, I enclose them in a
triple-quoted string) from each of the elements of the list.
In the end, I have wordlist:
['Tis', 'so', 'said', 'the', 'Duchess', 'and', 'the', 'moral', 'of',
'that', 'is', 'Oh', 'tis', 'love', 'tis', 'love', 'that', 'makes',
'the', 'world', 'go', 'round', '']
What about this? Was it confusing?
Roelof
Francesco
hello Franceso,
It was not confusing when I read your explanation.
Still im grazy wht with you and Joel the strip works and with me I get errors.
But how can I use the triple quotes when reading a textf-file ?
Roelof
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Re: [Tutor] FW: wierd replace problem
From: rwob...@hotmail.com To: sander.swe...@gmail.com Subject: RE: [Tutor] FW: wierd replace problem Date: Tue, 14 Sep 2010 17:40:28 + From: sander.swe...@gmail.com To: tutor@python.org Date: Tue, 14 Sep 2010 19:28:28 +0200 Subject: Re: [Tutor] FW: wierd replace problem - Original message - Look at the backslash! It doesn't strip the backslash in the string, but it escapes the double quote following it. I don't know how people can explain it any better. Maybe the link below makes it clear what backslash really does. http://pythonconquerstheuniverse.wordpress.com/2008/06/04/gotcha-%e2%80%94-backslashes-are-escape-characters/ Greets sander ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Oke, I get it. When I want to delete a I have to use a backslash. For me case closed. Everyone thanks for the patience and explanations. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] FW: wierd replace problem
Date: Tue, 14 Sep 2010 21:05:06 +0100 Subject: Re: [Tutor] FW: wierd replace problem From: wpr...@gmail.com To: rwob...@hotmail.com CC: tutor@python.org Roelof, On 14 September 2010 17:35, Roelof Wobben wrote: But how can I use the triple quotes when reading a textf-file ? To repeat what I said before, obviously not clearly enough: All the quoting stuff, escaping stuff, all of that ONLY APPLIES TO STRINGS/DATA INSIDE OF YOUR PYTHON CODE. It does NOT APPLY TO DATA INSIDE OF FILES! Why not to files? Because there's no ambiguity in data inside a file. It's understood that everything in a file is just data. By contrast, in Python code, quote characters have *meaning*. Specifically they indicate the start and end of string literals. So when they themselves are part of teh string you have to write them specially to indicate their meaning, either as closing the string, or as part of the string data. In a file by contrast, every character is presumed to be just a piece of data, and so quotes have no special inherent meaning to Python, so they just represent themselves and always just form part of the data being read from the file. Do you understand what I'm saying? If you have any doubt please respond so we can try to get this cleared up -- Unless and until you realise there's a difference between data in a file and string literals in your python source code you're not going to undertand what you're doing here. Regards, Walter I understand it but I try to understand why in a file there is this 'word python makes a 'word. I know that a file is just data but I thought that if that data is read in a string I could work with the quoting stuff. But im very wrong here. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] wierd replace problem
Hello,
I have this string called test with the contents of 'het is een wonder \\TIS'
Now I want to get rid of the \\ so I do this : test2 = test.replace ('\\', '')
And I get at the python prompt this answer : 'het is een wonder TIS'
So that's right.
Now I try the same in a IDE with this programm :
woorden =[]
letter_counts = {}
file = open ('alice_in_wonderland.txt', 'r')
for line in file:
line2 = line.replace (\\,)
line3 = line2.lower()
woorden = line3.split()
for letter in woorden:
letter_counts[letter] = letter_counts.get (letter, 0) + 1
letter_items = letter_counts.items()
letter_items.sort()
print letter_items
But now Im gettting this output :
[('\'tis', 1),
Why does the \ stays here. It should have gone as the test in the python prompt
says.
Roelof
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[Tutor] wierd replace problem
From: rwob...@hotmail.com
To: bgai...@gmail.com
Subject: RE: [Tutor] wierd replace problem
Date: Mon, 13 Sep 2010 15:19:12 +
Date: Mon, 13 Sep 2010 11:07:19 -0400
From: bgai...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On 9/13/2010 8:19 AM, Roelof Wobben wrote:
Hello,
I have this string called test with the contents of 'het is een wonder
\\TIS'
Now I want to get rid of the \\ so I do this : test2 = test.replace ('\\',
'')
And I get at the python prompt this answer : 'het is een wonder TIS'
So that's right.
Now I try the same in a IDE with this programm :
woorden =[]
letter_counts = {}
file = open ('alice_in_wonderland.txt', 'r')
for line in file:
line2 = line.replace (\\,)
line3 = line2.lower()
woorden = line3.split()
for letter in woorden:
letter_counts[letter] = letter_counts.get (letter, 0) + 1
letter_items = letter_counts.items()
letter_items.sort()
print letter_items
But now Im gettting this output :
[('\'tis', 1),
Why does the \ stays here. It should have gone as the test in the python
prompt says.
I ran your program against a 1 line file containing 'het is een wonder
\\TIS'
The result I get is [('een', 1), ('het', 1), ('is', 1), ('tis', 1),
('wonder', 1)]
Dunno why you are getting a different result.
Here is where using the debugger and going step by step can help. I have
no experience with the IDLE debugger. Perhaps others can offer advice on
that.
--
Bob Gailer
919-636-4239
Chapel Hill NC
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Hello everyone.
Chancing to (r\\, '') or (, '') did not help.
I know that there were more outcome. I would only let see that on the python
prompt the \ is deleted and if I use Eclipse the / stays when I use the text
from alice in wonderland.
And im still wondering why this happens.
Maybe put the text from alice into the python prompt and look what happens.
Roelof
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Re: [Tutor] wierd replace problem
Date: Mon, 13 Sep 2010 12:17:47 -0400
From: mich...@trollope.org
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On Mon, Sep 13, 2010 at 12:19:23PM +, Roelof Wobben wrote:
Hello,
I have this string called test with the contents of 'het is een wonder \\TIS'
Now I want to get rid of the \\ so I do this : test2 = test.replace ('\\', '')
And I get at the python prompt this answer : 'het is een wonder TIS'
So that's right.
Now I try the same in a IDE with this programm :
woorden =[]
letter_counts = {}
file = open ('alice_in_wonderland.txt', 'r')
for line in file:
line2 = line.replace (\\,)
line3 = line2.lower()
woorden = line3.split()
for letter in woorden:
letter_counts[letter] = letter_counts.get (letter, 0) + 1
letter_items = letter_counts.items()
letter_items.sort()
print letter_items
But now Im gettting this output :
[('\'tis', 1),
Why does the \ stays here. It should have gone as the test in the python
prompt says.
Hello,
Actually, on closer look I can see the answer.
The original text must look something like this:
\\'tis the season to be jolly, said santa.
When you run your process against a string in that format, you get the
output shown: ('\'tis', 1). The appearance of the backslash is
fortuitous. It has nothing to do with the string.replace(), it's
there to escape the single quote, which is appearing in the middle of
a single-quoted string. IF the double-quote had not also been there,
python would have replaced the outer quotes with double quotes, as it
does on my system before I got to thinking about that lonely double
quote.
Thanks.
mp
--
Michael Powe mich...@trollope.org Naugatuck CT USA
I wrote what I did because as a woman, as a mother, I was oppressed
and brokenhearted with the sorrows and injustice I saw, because as a
Christian I felt the dishonor to Christianity, -- because as a lover
of my country, I trembled at the coming day of wrath. -- H.B. Stowe
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Hello Michael,
The original text is this :
`'Tis so,' said the Duchess: `and the moral of that is--Oh,
'tis love, 'tis love, that makes the world go round!'
So I think I have to replace the '.
Roelof
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[Tutor] wierd replace problem
From: rwob...@hotmail.com
To: joel.goldst...@gmail.com
Subject: RE: [Tutor] wierd replace problem
Date: Mon, 13 Sep 2010 16:45:28 +
Date: Mon, 13 Sep 2010 12:42:56 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On Mon, Sep 13, 2010 at 12:37 PM, Roelof Wobben
wrote:
Date: Mon, 13 Sep 2010 12:17:47 -0400
From: mich...@trollope.org
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On Mon, Sep 13, 2010 at 12:19:23PM +, Roelof Wobben wrote:
Hello,
I have this string called test with the contents of 'het is een
wonder \\TIS'
Now I want to get rid of the \\ so I do this : test2 = test.replace
('\\', '')
And I get at the python prompt this answer : 'het is een wonder TIS'
So that's right.
Now I try the same in a IDE with this programm :
woorden =[]
letter_counts = {}
file = open ('alice_in_wonderland.txt', 'r')
for line in file:
line2 = line.replace (\\,)
line3 = line2.lower()
woorden = line3.split()
for letter in woorden:
letter_counts[letter] = letter_counts.get (letter, 0) + 1
letter_items = letter_counts.items()
letter_items.sort()
print letter_items
But now Im gettting this output :
[('\'tis', 1),
Why does the \ stays here. It should have gone as the test in the
python prompt says.
Hello,
Actually, on closer look I can see the answer.
The original text must look something like this:
\\'tis the season to be jolly, said santa.
When you run your process against a string in that format, you get the
output shown: ('\'tis', 1). The appearance of the backslash is
fortuitous. It has nothing to do with the string.replace(), it's
there to escape the single quote, which is appearing in the middle of
a single-quoted string. IF the double-quote had not also been there,
python would have replaced the outer quotes with double quotes, as it
does on my system before I got to thinking about that lonely double
quote.
Thanks.
mp
--
Michael Powe mich...@trollope.org
Naugatuck CT USA
I wrote what I did because as a woman, as a mother, I was oppressed
and brokenhearted with the sorrows and injustice I saw, because as a
Christian I felt the dishonor to Christianity, -- because as a lover
of my country, I trembled at the coming day of wrath. -- H.B. Stowe
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Hello Michael,
The original text is this :
`'Tis so,' said the Duchess: `and the moral of that is--Oh,
'tis love, 'tis love, that makes the world go round!'
So I think I have to replace the '.
Roelof
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That is a completely different problem than the one you originally
posed. I doubt that what you inserted above is actually completely
correct. It opens with a back tick, has a back tick before and, then
ens with what looks like a double quote then a single quote
--
Joel Goldstick
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Hello Joel,
The orginal text can be found here :
http://openbookproject.net/thinkcs/python/english2e/resources/ch10/alice_in_wonderland.txt
So you can see I copied it right.
Roelof
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Re: [Tutor] wierd replace problem
From: rwob...@hotmail.com
To: tutor@python.org
Date: Mon, 13 Sep 2010 16:46:09 +
Subject: [Tutor] wierd replace problem
From: rwob...@hotmail.com
To: joel.goldst...@gmail.com
Subject: RE: [Tutor] wierd replace problem
Date: Mon, 13 Sep 2010 16:45:28 +
Date: Mon, 13 Sep 2010 12:42:56 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On Mon, Sep 13, 2010 at 12:37 PM, Roelof Wobben
wrote:
Date: Mon, 13 Sep 2010 12:17:47 -0400
From: mich...@trollope.org
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On Mon, Sep 13, 2010 at 12:19:23PM +, Roelof Wobben wrote:
Hello,
I have this string called test with the contents of 'het is een
wonder \\TIS'
Now I want to get rid of the \\ so I do this : test2 = test.replace
('\\', '')
And I get at the python prompt this answer : 'het is een wonder TIS'
So that's right.
Now I try the same in a IDE with this programm :
woorden =[]
letter_counts = {}
file = open ('alice_in_wonderland.txt', 'r')
for line in file:
line2 = line.replace (\\,)
line3 = line2.lower()
woorden = line3.split()
for letter in woorden:
letter_counts[letter] = letter_counts.get (letter, 0) + 1
letter_items = letter_counts.items()
letter_items.sort()
print letter_items
But now Im gettting this output :
[('\'tis', 1),
Why does the \ stays here. It should have gone as the test in the
python prompt says.
Hello,
Actually, on closer look I can see the answer.
The original text must look something like this:
\\'tis the season to be jolly, said santa.
When you run your process against a string in that format, you get the
output shown: ('\'tis', 1). The appearance of the backslash is
fortuitous. It has nothing to do with the string.replace(), it's
there to escape the single quote, which is appearing in the middle of
a single-quoted string. IF the double-quote had not also been there,
python would have replaced the outer quotes with double quotes, as it
does on my system before I got to thinking about that lonely double
quote.
Thanks.
mp
--
Michael Powe mich...@trollope.org
Naugatuck CT USA
I wrote what I did because as a woman, as a mother, I was oppressed
and brokenhearted with the sorrows and injustice I saw, because as a
Christian I felt the dishonor to Christianity, -- because as a lover
of my country, I trembled at the coming day of wrath. -- H.B. Stowe
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Hello Michael,
The original text is this :
`'Tis so,' said the Duchess: `and the moral of that is--Oh,
'tis love, 'tis love, that makes the world go round!'
So I think I have to replace the '.
Roelof
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That is a completely different problem than the one you originally
posed. I doubt that what you inserted above is actually completely
correct. It opens with a back tick, has a back tick before and, then
ens with what looks like a double quote then a single quote
--
Joel Goldstick
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Hello Joel,
The orginal text can be found here :
http://openbookproject.net/thinkcs/python/english2e/resources/ch10/alice_in_wonderland.txt
So you can see I copied it right.
Roelof
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Hello,
I tried my programm in IDLE and the problem stays.
So I think it has to do with the text-file and how python reads it.
Roelof
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Re: [Tutor] wierd replace problem
To: tutor@python.org
From: alan.ga...@btinternet.com
Date: Mon, 13 Sep 2010 18:28:46 +0100
Subject: Re: [Tutor] wierd replace problem
Roelof Wobben wrote
Now I want to get rid of the \\ so I do this : test2 = test.replace
('\\', '')
And I get at the python prompt this answer : 'het is een wonder TIS'
So that's right.
OK,. Thats replacing a double slash in the data
for line in file:
line2 = line.replace (\\,)
And this is doing the same. Any double slashes in your file content
will be replaced.
letter_items = letter_counts.items()
letter_items.sort()
print letter_items
Now we have an issue of representing characters.
[('\'tis', 1),
This is a representation issue. Python is using the \ to escape
the single quote since you are using single quotes on the outside.
Without the backslash the \' would look like the end of the
string to Python.
If you print the actual string it will not show the quote:
for item in letter_items:
print item[0]
Backslashes are awkward characters because they are used
for several different special purposes as well as being characters
in their own right. If you had tried replacing almost any other
character you would not have gotten confused.
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
Why does the \ stays here. It should have gone as the test in the
python prompt says.
Roelof
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hello Alan,
Your right. Then it prints like this 'tis
Which is not right. It must be tis.
So the replace does not what it supposed to do.
Roelof
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[Tutor] FW: wierd replace problem
From: rwob...@hotmail.com To: bgai...@gmail.com Subject: RE: [Tutor] wierd replace problem Date: Mon, 13 Sep 2010 18:19:43 + Date: Mon, 13 Sep 2010 14:08:46 -0400 From: bgai...@gmail.com To: tutor@python.org Subject: Re: [Tutor] wierd replace problem On 9/13/2010 1:50 PM, Roelof Wobben wrote: [snip] hello Alan, Your right. Then it prints like this 'tis Which is not right. It must be tis. So the replace does not what it supposed to do. Sorry but I am now more confused. After discovering no \ in the text file now you seem to have have a new specification, which is to get rid of the '. I suggest you give a clear, complete and correct problem statement. Right now we are shooting in the dark at a moving target. Something like. Given the file alice_in_wonderland.txt, copied from url so-and-so Remove these characters ... Split into words (not letters?) where word is defined as Count the frequency of each word. -- Bob Gailer 919-636-4239 Chapel Hill NC ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello, The problem as stated in the book is : 3.Write a program called alice_words.py that creates a text file named alice_words.txt containing an alphabetical listing of all the words found in alice_in_wonderland.txt together with the number of times each word occurs. The first 10 lines of your output file should look something like this: Word Count === a 631 a-piece 1 abide 1 able 1 about 94 above 3 absence 1 absurd 2How many times does the word, alice, occur in the book? The text can be found here : http://openbookproject.net/thinkcs/python/english2e/resources/ch10/alice_in_wonderland.txt So I open the file. Read the first rule. This is no problem for me. Then I want to remove some characters like ' , when the word in the text begins with these characters. And there is the problem. The ' and can't be removed with replace. So in the output you will see something like this dark instead of dark word is the words of the sentence which is read in from the text-file. Am i now clear what the problem is Im facing. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] FW: wierd replace problem
From: rwob...@hotmail.com
To: joel.goldst...@gmail.com
Subject: RE: [Tutor] wierd replace problem
Date: Mon, 13 Sep 2010 18:23:36 +
Date: Mon, 13 Sep 2010 14:18:36 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On Mon, Sep 13, 2010 at 2:08 PM, bob gailer
wrote:
On 9/13/2010 1:50 PM, Roelof Wobben wrote:
[snip]
hello Alan,
Your right. Then it prints like this 'tis
Which is not right. It must be tis.
So the replace does not what it supposed to do.
Sorry but I am now more confused. After discovering no \ in the text
file now you seem to have have a new specification, which is to get rid
of the '.
I suggest you give a clear, complete and correct problem statement.
Right now we are shooting in the dark at a moving target.
Something like.
Given the file alice_in_wonderland.txt, copied from url so-and-so
Remove these characters ...
Split into words (not letters?) where word is defined as
Count the frequency of each word.
--
Bob Gailer
919-636-4239
Chapel Hill NC
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How about using str.split() to put words in a list, then run strip()
over each word with the required characters to be removed ('`)
--
Joel Goldstick
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Hello Joel.
That can be a solution but when i have --dark the -- must be removed.
But in a-piece the - must not be removed.
Roelof
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Re: [Tutor] FW: wierd replace problem
Date: Mon, 13 Sep 2010 15:31:08 -0400
Subject: Re: [Tutor] FW: wierd replace problem
From: joel.goldst...@gmail.com
To: rwob...@hotmail.com
On Mon, Sep 13, 2010 at 2:24 PM, Roelof Wobben
wrote:
From: rwob...@hotmail.com
To: joel.goldst...@gmail.com
Subject: RE: [Tutor] wierd replace problem
Date: Mon, 13 Sep 2010 18:23:36 +
Date: Mon, 13 Sep 2010 14:18:36 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] wierd replace problem
On Mon, Sep 13, 2010 at 2:08 PM, bob gailer
wrote:
On 9/13/2010 1:50 PM, Roelof Wobben wrote:
[snip]
hello Alan,
Your right. Then it prints like this 'tis
Which is not right. It must be tis.
So the replace does not what it supposed to do.
Sorry but I am now more confused. After discovering no \ in the text
file now you seem to have have a new specification, which is to get rid
of the '.
I suggest you give a clear, complete and correct problem statement.
Right now we are shooting in the dark at a moving target.
Something like.
Given the file alice_in_wonderland.txt, copied from url so-and-so
Remove these characters ...
Split into words (not letters?) where word is defined as
Count the frequency of each word.
--
Bob Gailer
919-636-4239
Chapel Hill NC
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How about using str.split() to put words in a list, then run strip()
over each word with the required characters to be removed ('`)
--
Joel Goldstick
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Hello Joel.
That can be a solution but when i have --dark the -- must be removed.
But in a-piece the - must not be removed.
Roelof
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strip only removes from start and end of string. Not from the middle,
so a-piece would stay as a word
--
Joel Goldstick
Oke,
I have tried that but then I see this message :
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 8
letter2 = letter.strip('`)
^
SyntaxError: EOL while scanning string literal
Change it to (''`) do not help either.
Roelof
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[Tutor] recursive problem
From: rwob...@hotmail.com To: st...@pearwood.info Subject: RE: [Tutor] recursive problem Date: Sun, 12 Sep 2010 07:58:48 + From: st...@pearwood.info To: tutor@python.org Date: Sun, 12 Sep 2010 10:10:53 +1000 Subject: Re: [Tutor] recursive problem On Sun, 12 Sep 2010 09:03:49 am Walter Prins wrote: So, perhaps it's an idea to call dir() on a given object and see whether the object provides the necessary methods to function, e.g. __iter__, __delitem__, __setitem__ and friends? There's no need to do this: attributes = dir(obj) if '__iter__' in attributes and '__len__' in attributes: print Quacks like a list else: print Not like a list when you can do this: if hasattr(obj, '__iter__') and hasattr(obj, '__len__'): print Quacks like a list else: print Not like a list or this: try: obj.__iter__ obj.__len__ except AttributeError: print Not like a list else: print Quacks like a list or even try: iter(obj) len(obj) except TypeError: print Not like a list else: print Quacks like a list Where possible, the last version is to be preferred, because it doesn't care about internal details which might change. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Oke, This is to far for me. Im only at chapter 11 and this stuff will be in chapter 13 and further. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] tree problem
Hello, I have this problem. Write a program named litter.py that creates an empty file named trash.txt in each subdirectory of a directory tree given the root of the tree as an argument (or the current directory as a default). So I change the example to this : def traverse(path, s='.\n', f=0, d=0): path2file = os.path.join(path) *** pathfile contains the path if os.path.isdir(path2file): if pathfile is a dir. d += 1 * the is one more directory if getdirlist(path2file): ** if the outcome of getdirlist is the same as the current directory s, f, d = traverse(path2file, '| ' + s, f, d) do this module again else: f += 1 ** else f (number of files increases with 1 return s, f, d ** return s , numbers of files and the number of directories. When I try to make it run I get this message : File C:\Users\wobben\workspace\oefeningen\src\test.py, line 31, in traverse s, f, d = traverse(path2file, '| ' + s, f, d) File C:\Users\wobben\workspace\oefeningen\src\test.py, line 31, in traverse s, f, d = traverse(path2file, '| ' + s, f, d) File C:\Users\wobben\workspace\oefeningen\src\test.py, line 31, in traverse s, f, d = traverse(path2file, '| ' + s, f, d) File C:\Users\wobben\workspace\oefeningen\src\test.py, line 28, in traverse if os.path.isdir(path2file): File C:\Python27\lib\genericpath.py, line 44, in isdir return stat.S_ISDIR(st.st_mode) File C:\Python27\lib\stat.py, line 41, in S_ISDIR return S_IFMT(mode) == S_IFDIR RuntimeError: maximum recursion depth exceeded I can't see why this happens. I know I have to fish but I can't see what's wrong here. So I hope someone can learn how to fish here. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] tree problem
Subject: Re: [Tutor] tree problem
From: evert@gmail.com
Date: Sun, 12 Sep 2010 13:29:12 +0200
CC: tutor@python.org
To: rwob...@hotmail.com
Write a program named litter.py that creates an empty file named trash.txt
in each subdirectory of a directory tree given the root of the tree as an
argument (or the current directory as a default).
So I change the example to this :
def traverse(path, s='.\n', f=0, d=0):
path2file = os.path.join(path) *** pathfile contains the path
if os.path.isdir(path2file): if pathfile is a dir.
d += 1 * the is one more directory
if getdirlist(path2file): ** if the outcome of getdirlist is the same as
the current directory
s, f, d = traverse(path2file, '| ' + s, f, d) do this module again
else:
f += 1 ** else f (number of files increases with 1
return s, f, d ** return s , numbers of files and the number of
directories.
That can't be a valid program: no indentation, comments not preceded by a
comment mark (#), and getdirlist is nowhere defined afaics. While probably
anyone can understand what's the real code of the above snippet, it doesn't
help putting non-valid code like this in your email. If you can directly
copy-paste code (plain text), that is almost always better.
When I try to make it run I get this message :
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 31, in traverse
s, f, d = traverse(path2file, '| ' + s, f, d)
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 31, in traverse
s, f, d = traverse(path2file, '| ' + s, f, d)
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 31, in traverse
s, f, d = traverse(path2file, '| ' + s, f, d)
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 28, in traverse
if os.path.isdir(path2file):
File C:\Python27\lib\genericpath.py, line 44, in isdir
return stat.S_ISDIR(st.st_mode)
File C:\Python27\lib\stat.py, line 41, in S_ISDIR
return S_IFMT(mode) == S_IFDIR
RuntimeError: maximum recursion depth exceeded
I can't see why this happens.
I know I have to fish but I can't see what's wrong here.
So I hope someone can learn how to fish here.
Fishing is debugging. You could use the logging module for that, but assuming
you're not familiar with that, litter your program with print statements, and
print out the value of the various variables at certain points in your
program (it helps putting a short string in the print statement as well, so
you know which print statement print where. Eg, print '1:', s, f, d; and then
a few lines below, print '2:', s, f, d).
Having done that (you will get a lot of output), try to follow the logic of
the program and see why things happen the way they do. In this case, why you
keep spiraling in and never break out of your recursion. Then, step by step,
you can try and change or add statements so you actually find a way to break
out the recursion.
Evert
Hello Evert.
Sorry but the change to plain text destroyed also this.
What I have it this.
def getdirlist(path):
dirlist = os.listdir(path)
dirlist = [name for name in dirlist if name[0] != '.']
dirlist.sort()
return dirlist
def traverse(path, s='.\n', f=0, d=0):
dirlist = getdirlist(path)
for file in enumerate(dirlist):
print file
path2file = os.path.join(path)
if os.path.isdir(path2file):
d += 1
if getdirlist(path2file):
print path2file
myfile = open ('trash.txt', 'w')
myfile.close ()
return s, f, d
The file is made. Now find out why it doesn't go into the next level.
With this : s, f, d = traverse(path2file, '| ' + s, f, d) I goes into a loop
which never ends.
Roelof
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Re: [Tutor] tree problem
Date: Sun, 12 Sep 2010 09:46:08 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] tree problem
On Sun, Sep 12, 2010 at 9:32 AM, Roelof Wobben
wrote:
Date: Sun, 12 Sep 2010 09:08:18 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] tree problem
On Sun, Sep 12, 2010 at 7:54 AM, Lie Ryan
wrote:
On 09/12/10 21:15, Roelof Wobben wrote:
Hello,
I have this problem.
Write a program named litter.py that creates an empty file named
trash.txt in each subdirectory of a directory tree given the root of
the tree as an argument (or the current directory as a default).
By default, Python has a recursion limit of 1000 deep; that is, your
function is calling itself 1000 times without returning.
In this case, the only reason why you hit the recursion limit is if you
have a directory which is 1000 deep (quite unlikely, Windows has a
directory depth limit much lower than that).
Or your function somehow never returns, in a typical recursive function,
it's usually because you have problem in the precondition.
You really have two problems here:
1. You need to know how to write an empty file with the name
litter.py. You should probably write a function to see if you can do
that. That's pretty easy
2. You need to traverse a tree. I see you are using os module. You
should try help(os) while in your python shell to learn what methods
are available. Traversing a tree is also sometimes called 'walking'
good luck
--
Joel Goldstick
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Hello Joel.
Youre right.
Problem 1 is easily solved by using myfile = open ('filename', 'w')
followed by myfile.close()
Problem 2 is more difficult.
I have to use recursion and as example the source of the tree command
in linux is given.
The traverse module looks like this :
def traverse(path, prefix='|--', s='.\n', f=0, d=0):
what's up with the prefix???
dirlist = getdirlist(path)
for num, file in enumerate(dirlist):
why are you using enumerate? it gives you num which you never use
for file in dirlist gives what you seem to be using
lastprefix = prefix[:-3] + '``--'
dirsize = len(dirlist)
if num dirsize - 1:
s += '%s %s\n' % (prefix, file)
else:
s += '%s %s\n' % (lastprefix, file)
path2file = os.path.join(path, file)
if os.path.isdir(path2file):
d += 1
if getdirlist(path2file):
s, f, d = traverse(path2file, '| ' + prefix, s, f, d)
else:
f += 1
return s, f, d
For me it looks like the pathfile = os.path.join(path, file)
and then the s.f.d. rule take care that a subdir is entered.
what are s.f.d. Can you use more descriptive names
Am I right on this ?
Roelof
--
Joel Goldstick
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Hello,
I solved this by this programm :
import os
import sys
def getroot():
if len(sys.argv) == 1:
path = ''
else:
path = sys.argv[1]
if os.path.isabs(path):
tree_root = path
else:
tree_root = os.path.join(os.getcwd(), path)
return tree_root
def getdirlist(path):
dirlist = os.listdir(path)
dirlist = [name for name in dirlist if name[0] != '.']
dirlist.sort()
return dirlist
def traverse(path, s='.\n', f=0, d=0):
file = os.path.join(path,'trash.txt')
myfile = open (file, 'w')
myfile.close()
dirlist = getdirlist(path)
for num, file in enumerate(dirlist):
dirsize = len(dirlist)
if num dirsize - 1:
s += '%s \n' % (file)
else:
s += '%s \n' % (file)
path2file = os.path.join(path, file)
if os.path.isdir(path2file):
d += 1
s, f, d = traverse(path2file, '| ' + s, f, d)
return s,f,d
if __name__ == '__main__':
root = getroot()
tree_str, files, dirs = traverse(root)
Roelof
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Re: [Tutor] tree problem
Date: Sun, 12 Sep 2010 13:40:09 -0400
Subject: Re: [Tutor] tree problem
From: joel.goldst...@gmail.com
To: rwob...@hotmail.com
On Sun, Sep 12, 2010 at 1:20 PM, Roelof Wobben
wrote:
Date: Sun, 12 Sep 2010 11:59:07 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] tree problem
On Sun, Sep 12, 2010 at 10:48 AM, Roelof Wobben
wrote:
Date: Sun, 12 Sep 2010 09:46:08 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] tree problem
On Sun, Sep 12, 2010 at 9:32 AM, Roelof Wobben
wrote:
Date: Sun, 12 Sep 2010 09:08:18 -0400
From: joel.goldst...@gmail.com
To: tutor@python.org
Subject: Re: [Tutor] tree problem
On Sun, Sep 12, 2010 at 7:54 AM, Lie Ryan
wrote:
On 09/12/10 21:15, Roelof Wobben wrote:
Hello,
I have this problem.
Write a program named litter.py that creates an empty file named
trash.txt in each subdirectory of a directory tree given the root of
the tree as an argument (or the current directory as a default).
By default, Python has a recursion limit of 1000 deep; that is, your
function is calling itself 1000 times without returning.
In this case, the only reason why you hit the recursion limit is if you
have a directory which is 1000 deep (quite unlikely, Windows has a
directory depth limit much lower than that).
Or your function somehow never returns, in a typical recursive function,
it's usually because you have problem in the precondition.
You really have two problems here:
1. You need to know how to write an empty file with the name
litter.py. You should probably write a function to see if you can do
that. That's pretty easy
2. You need to traverse a tree. I see you are using os module. You
should try help(os) while in your python shell to learn what methods
are available. Traversing a tree is also sometimes called 'walking'
good luck
--
Joel Goldstick
___ Tutor maillist -
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subscription options:
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Hello Joel.
Youre right.
Problem 1 is easily solved by using myfile = open ('filename', 'w')
followed by myfile.close()
Problem 2 is more difficult.
I have to use recursion and as example the source of the tree command
in linux is given.
The traverse module looks like this :
def traverse(path, prefix='|--', s='.\n', f=0, d=0):
what's up with the prefix???
dirlist = getdirlist(path)
for num, file in enumerate(dirlist):
why are you using enumerate? it gives you num which you never use
for file in dirlist gives what you seem to be using
lastprefix = prefix[:-3] + '``--'
dirsize = len(dirlist)
if num dirsize - 1:
s += '%s %s\n' % (prefix, file)
else:
s += '%s %s\n' % (lastprefix, file)
path2file = os.path.join(path, file)
if os.path.isdir(path2file):
d += 1
if getdirlist(path2file):
s, f, d = traverse(path2file, '| ' + prefix, s, f, d)
else:
f += 1
return s, f, d
For me it looks like the pathfile = os.path.join(path, file)
and then the s.f.d. rule take care that a subdir is entered.
what are s.f.d. Can you use more descriptive names
Am I right on this ?
Roelof
--
Joel Goldstick
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Hello,
I solved this by this programm :
import os
import sys
def getroot():
if len(sys.argv) == 1:
path = ''
else:
path = sys.argv[1]
if os.path.isabs(path):
tree_root = path
else:
tree_root = os.path.join(os.getcwd(), path)
return tree_root
def getdirlist(path):
dirlist = os.listdir(path)
dirlist = [name for name in dirlist if name[0] != '.']
dirlist.sort()
return dirlist
def traverse(path, s='.\n', f=0, d=0):
file = os.path.join(path,'trash.txt')
myfile = open (file, 'w')
myfile.close()
dirlist = getdirlist(path)
for num, file in enumerate(dirlist):
dirsize = len(dirlist)
if num dirsize - 1:
s += '%s \n' % (file)
else:
s += '%s \n' % (file)
path2file = os.path.join(path, file)
if os.path.isdir(path2file):
d += 1
s, f, d = traverse(path2file, '| ' + s, f, d)
return s,f,d
if __name__ == '__main__':
root = getroot()
tree_str, files, dirs = traverse(root)
Roelof
Good for you. Some questions:
What do you mean to be happening here:
if num dirsize - 1:
s += '%s \n' % (file)
else:
s += '%s \n' % (file)
it does the same thing in either case
What exactly does s do for you?
You use the first parameter 'path' in your calls to traverse, but I
don't see how you are using f or d anywhere either
--
Joel Goldstick
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Re: [Tutor] recursive problem
To: tutor@python.org From: alan.ga...@btinternet.com Date: Sun, 12 Sep 2010 20:52:06 +0100 Subject: Re: [Tutor] recursive problem Roelof Wobben wrote I guess the question to ask/consider is: How can be establish whether a particular object supports a particular interface/set of behaviours In general we try it and handle the exceptions that we require? E.g. how do we most pythonically check whether some object walks like a list and quacks like a list without tying such code to explicit type checking? But the risk is that although it may quack, it does so like a missile launch program rather than a list - oops! :-) With the knowlegde I have from the few chapters of thinking like a computer scientist I don't know the answer to the last question. If you do need to avoid accidentally launching missiles then you need to do some type checking - although ideally using isinstance() instead of type(). But in the majority of cases some sensible documentation and Python's culture that we are all adults here usually means you don't need to. HTH, -- Alan Gauld Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Alan, The last chapter I don't understand completly. Do i have no need for type checking or make use of isinstance() or do I misunderstood you. Sorry that English is not a language I speak very well. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] exceptions problem
Date: Sat, 11 Sep 2010 11:05:54 -0400 From: bgai...@gmail.com To: tutor@python.org Subject: Re: [Tutor] exceptions problem On 9/11/2010 6:56 AM, Peter Otten wrote: Steven D'Aprano wrote: On Sat, 11 Sep 2010 09:56:41 am bob gailer wrote: I never thought that you can use a float and a integer to look if the number is a integer. You can't. I made that comment in the context of the OPs function: def readposint(): x = raw_input(Please enter a positive integer :) try: if (int(x)0 or (float(x) - int(x) 0)): raise(ValueError) except: print x , is not a positive integer. Try again. return -1 return x The OP thought (incorrectly) that, given for example: x = '3.1' float(x) - int(x) would evaluate to 0.1 In reality int(x) in this case raises an exception. ValueError: invalid literal for int() with base 10: '3.1' Since the expression was in a try he could not tell exactly what was happening. I also don't quite understand the use of raise in the try. I wish and hope that Roelof will learn how to do program walkthroughs and use the interactive prompt to solve things himself. I applaud the patience some of you have ih hand-holding him. I don't have that patience. I wish him to learn to fish. -- Bob Gailer 919-636-4239 Chapel Hill NC ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Bob, Oke, I try to fish. When I do x= a y= int(x) Then I get ValueError. When I do x= 1.2 y=int(x) No exception is raised. But when I do then x ==y I get a false. When I now do float(x) - int(x) I get 1.2 - 1 = 0.2 and that's greater then 0 Because one of the two is true the Raise is executed. x = -9 y=int(x) No exception is raised. X == y is True. But float(x) - int(x) I get 0.0 and 0.0 0 is False. Because x == y is True the Raise is executed. Are these the right conclusions ?? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] recursive problem
From: st...@pearwood.info To: tutor@python.org Date: Sun, 12 Sep 2010 03:18:19 +1000 Subject: Re: [Tutor] recursive problem On Fri, 10 Sep 2010 09:30:23 pm Ewald Horn wrote: While EAFP is great, it's not always the best way to proceed. That, at least, is correct. But what you say next is not: Sometimes you want programs to be very robust and secure, this is where LBYL comes in - it is quite often used in online transaction processing and other areas where absolute certainty is more important than any other consideration. If what you are saying is correct, and I doubt seriously that it is, then chances are good that they're not succeeding in their aim. EAFP tends to use less code and is faster to use, while LBYL principles makes your program more bulletproof. That's almost 100% backwards. Let's take a simple example: you want to open a file, and deal with the case of the file being missing: filename = 'myfile.txt' # whatever... fp = open(filename) do_something_with(fp) Let's add some error checking. With EAFP, you get this: try: fp = open(filename) except IOError: handle_error() With LBYL, you get: if os.path.exists(filename): fp = open(filename) else: handle_error() The amount of code is about the same, but the try...except block automatically handles a whole slew of errors -- missing files, permission denied, bad file names, corrupt disks, all sorts of things that would be difficult or tedious to Look Before You Leap. Some of these things -- like disk corruption -- you simply can't check ahead of time. There is no way of knowing if a file is corrupt without actually opening and/or reading from it. It gets worse. Your computer is a multitasking system. Virtually all computers are these days, yes, even the iPhone. Even if os.path.exists returns True, there is no guarantee that the file will still be there a millisecond later when you try to open it. Perhaps the operating system, or some other process, has deleted the file or renamed it. That's a bug waiting to happen -- a race condition. So if you're silly, you write this: if os.path.exists(filename): try: fp = open(filename) except IOError: handle_error() else: handle_error() If you're sensible, you realise that for reliable, secure code, checking for existence *before* opening the file is a waste of time and energy. It's barely acceptable for quick and dirty scripts, certainly not for high reliability applications. This is not the only sort of race condition. Imagine you're writing one of these high reliability online transactions you talked about, and you want to transfer money from one account to another: amount = 1000.00 if balance= amount: transfer(old_account, new_account, amount) else: insufficient_balance() Wait a second... that looks almost exactly like the LBYL code above, and it is vulnerable to the same sort of race condition if multiple processes can connect to the account at the same time. Does your bank allow you to log in twice? Does it have automatic transfers? If so, then one process can be transferring money while the other is checking the balance, and you have a bug waiting to happen. In practice, the banks allow accounts to become temporarily overdrawn, and often charge you for the privilege. And they write complicated code that looks like this: lock_id = lock_account() # Stop anything else from transferring funds. while lock_id == 0 # Lock failed, wait a second and try again. time.sleep(1) lock_id = lock_account() if number_of_attempts() 10: handle_error(internal error, please try again) # Now it's safe to check the balance. if balance= amount: transfer(old_account, new_account, amount, lock_id) else: insufficient_balance() # Don't forget to unlock the account, or there will be trouble later! errcode = unlock_account(lock_id) if errcode != 0: # This should never happen. If it does, it might mean the lock ID # is incorrect (how?), but probably means the database is corrupt. log_serious_error(errcode, lock_id) It's ugly and error-prone, but it's also a kind of EAFP: instead of checking whether a lock is available, and then taking it, you just try to acquire a lock, and deal with the consequences of not receiving one if it fails. The only difference is that you're manually checking an error code rather than catching an exception. Whatever mechanism is used for EAFP, it is most often shorter, simpler, more reliable and safer than LBYL. So why would anyone ever use LBYL? Well, sometimes it is more convenient for quick and dirty scripts, such as using os.path.exists. But more importantly, sometimes you need a transaction to apply in full, or not at all. You can't do this: try: do_this() do_that() do_something_else() except Exception: do_error() because if do_this() succeeds and do_that() fails, you might leave your data is a seriously inconsistent or
Re: [Tutor] recursive problem
From: st...@pearwood.info To: tutor@python.org Date: Sun, 12 Sep 2010 03:27:42 +1000 Subject: Re: [Tutor] recursive problem On Sun, 12 Sep 2010 03:18:19 am Steven D'Aprano wrote: But that hasn't done anything to prevent race conditions. So the real reason people use LBYL is that they're too lazy to write hideously ugly, but reliable, code, and they're just hoping that they will never expose the race condition. (Often this is a pretty safe hope, but not always.) http://en.wikipedia.org/wiki/Ostrich_algorithm -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Oke, But why is type checking then wrong. Lets says I want a module who must work on strings, tuple and lists. Can I then use EAFP ? Without type checking I never know which one is used now. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] recursive problem
From: rwob...@hotmail.com To: wpr...@gmail.com Subject: RE: [Tutor] recursive problem Date: Sat, 11 Sep 2010 18:05:12 + Date: Sat, 11 Sep 2010 19:01:39 +0100 Subject: Re: [Tutor] recursive problem From: wpr...@gmail.com To: rabidpoob...@gmail.com CC: rwob...@hotmail.com; tutor@python.org That's the whole point! You don't WANT to know what type it is. You want to just use it how you want, an if it behaves properly, who cares what type it is? See when you type check you are forcing the user to use those types. What if they want to derive a subclass from list? Is there really a reason why you should prevent them from using that subclass with your function? If there is a valid reason, type checking is fine. But if there isn't, type checking is just making your code more inflexible. Well, I would submit that if were going to do type checking in such a context you'd probably check for a base class, so deriving a subclass wouldn't break entirely. Your point still stands however, we don't even want to require from users to derive from class list. We'd be quite happy to work with any object that walks like a list and quacks like a list, that's the beauty of duck typing... I guess the question to ask/consider is: How can be establish whether a particular object supports a particular interface/set of behaviours that we require? E.g. how do we most pythonically check whether some object walks like a list and quacks like a list without tying such code to explicit type checking? Walter Exactly what I mean. With the knowlegde I have from the few chapters of thinking like a computer scientist I don't know the answer to the last question. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] recursive problem
From: st...@pearwood.info To: tutor@python.org Date: Sun, 12 Sep 2010 04:03:43 +1000 Subject: Re: [Tutor] recursive problem On Sun, 12 Sep 2010 03:40:38 am Roelof Wobben wrote: But why is type checking then wrong. Lets says I want a module who must work on strings, tuple and lists. It's not *always* wrong, but let me ask you... why do you want to *limit* the function to work on ONLY strings, tuples and lists? The Python philosophy is duck typing -- if it walks like a duck, and swims like a duck, it is close enough to a duck that we don't care that it's not actually a duck, but a goose. Here's an example: def f1(x): if type(x) is int or type(x) is float: print(x + 1 = %s % (x+1)) else: print(x is not a number) def f2(x): try: print(x + 1 = %s % (x+1)) except (ValueError, TypeError): print(x is not a number) f1(3) x + 1 = 4 from decimal import Decimal f1(Decimal(3)) x is not a number f2(Decimal(3)) x + 1 = 4 Function f1 makes the assumption that only ints and floats can be added, and so it gives the wrong results with Decimal numbers. But function f2 uses duck typing -- it doesn't care what sort of number x is, only that it can be added. Can I then use EAFP ? Without type checking I never know which one is used now. Going back to type-checking... sometimes you can't avoid it. Sometimes you use it because it is easier, and you don't care enough to write more complicated code. Sometimes you really do care what the type is: abc[2.0] Traceback (most recent call last): File , line 1, in TypeError: string indices must be integers -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Steven, Because I follow this book Thinking like a computer scientist and I have only read the chapters about strings. lists and tuples. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] recursive problem
From: rwob...@hotmail.com To: st...@pearwood.info Subject: RE: [Tutor] recursive problem Date: Sat, 11 Sep 2010 18:39:31 + From: st...@pearwood.info To: tutor@python.org Date: Sun, 12 Sep 2010 04:19:57 +1000 Subject: Re: [Tutor] recursive problem On Sun, 12 Sep 2010 04:09:20 am Roelof Wobben wrote: On Sun, 12 Sep 2010 03:40:38 am Roelof Wobben wrote: But why is type checking then wrong. Lets says I want a module who must work on strings, tuple and lists. It's not *always* wrong, but let me ask you... why do you want to *limit* the function to work on ONLY strings, tuples and lists? Because I follow this book Thinking like a computer scientist and I have only read the chapters about strings. lists and tuples. Good answer! Don't worry about all the complications. Learn to walk first, then learn to run. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Oke, So EAFP for me is one step to far ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] recursive problem
Hello ,
So my book teach me the wrong principle.
But can everything programmed on Eafp.
If you dont know if something is a list, a tuple or a string, you can get a lot
of nested try except think.
Roelof
Subject: Re: [Tutor] recursive problem
From: rabidpoob...@gmail.com
Date: Thu, 9 Sep 2010 15:32:44 -0500
To: rwob...@hotmail.com
No you misunderstood me. Eafp is a python design principle. lbyl is common in
older languages. Please reply all in the future so our discussion takes place
on the list instead of just between us.
Sent from my iPhone
On Sep 9, 2010, at 1:31 PM, Roelof Wobben rwob...@hotmail.com wrote:
Oke,
So If I understand you right LBYL is more the python way.
Wierd that the book im following (Thinking like a computer scientist) is more
EAFP.
Roelof
Subject: Re: [Tutor] recursive problem
From: rabidpoob...@gmail.com
Date: Thu, 9 Sep 2010 13:24:06 -0500
To: rwob...@hotmail.com
It's easier to ask for forgiveness than permission vs. Look before you leap. An
example of LBYL would be checking the type of a variable before you use it.
EAFP would be just using the variable, and if something goes wrong, handle the
exception. It's a core tenet of python software design and goes hand in hand w/
duck typing and other principles.
Sent from my iPhone
On Sep 9, 2010, at 1:16 PM, Roelof Wobben rwob...@hotmail.com wrote:
Sorry.
Im also new to Python and programming.
What does EAFP and LBYL mean ?
Roelof
From: rabidpoob...@gmail.com
Date: Thu, 9 Sep 2010 12:59:46 -0500
To: joel.goldst...@gmail.com
CC: tutor@python.org
Subject: Re: [Tutor] recursive problem
Nope Joel, that's what I meant. Remember EAFP over LBYL! I'm not sure the best
way to make sure the object is iterable though.
Sent from my iPhone
On Sep 9, 2010, at 11:41 AM, Joel Goldstick joel.goldst...@gmail.com wrote:
On Thu, Sep 9, 2010 at 12:07 PM, Steven D'Aprano st...@pearwood.info wrote:
On Fri, 10 Sep 2010 01:05:22 am Joel Goldstick wrote:
On Thu, Sep 9, 2010 at 10:26 AM, Luke Paireepinart
rabidpoob...@gmail.comwrote:
Shouldn't there be a way to do this without type checking? Duck
typing!
Your post got me thinking. Maybe better to test if the object can
return
an iter method. If it throws an error, then look at its value. If
it doesn't, then its a list or a tuple
It's not clear what you mean by return an iter method. Taken
literally, that would imply the object is a function. I think you
mean *has* an iter method -- except that's not right either:
[].iter
Traceback (most recent call last):
File stdin, line 1, in module
AttributeError: 'list' object has no attribute 'iter'
Perhaps you mean an object which can be passed to iter(), but lots of
objects can do that, not just lists and tuples:
iter(not a list or tuple)
str_iterator object at 0xb7d3520c
iter({1: None, 2: a, 4: 5})
dict_keyiterator object at 0xb7d3420c
I was googling, and found that if an object has an __iter__ method it will
return it. If not it will throw an error. You are right about more than lists
and tuples being iterable. But, in this thread, it was brought up that
checking type may not be pythonic. If you wanted to use the same code to find
values in a nested list of any objects, you could dispense with the type
checking and just see if it is iterable.
I'm new to python. Am I off base?
--
Steven D'Aprano
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--
Joel Goldstick
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[Tutor] exceptions problem
Hello, I have this problem : Write a function named readposint that prompts the user for a positive integer and then checks the input to confirm that it meets the requirements. A sample session might look like this: num = readposint() Please enter a positive integer: yes yes is not a positive integer. Try again. Please enter a positive integer: 3.14 3.14 is not a positive integer. Try again. Please enter a positive integer: -6 -6 is not a positive integer. Try again. Please enter a positive integer: 42 num 42 num2 = readposint(Now enter another one: ) Now enter another one: 31 num2 31 Now I thought this would work:def readposint(): x = raw_input(Please enter a positive integer :) try: x = int(x) and x 0 except: print x , is not a positive integer. Try again. return False return Truey = readposint() print y while y == False: readposint() print You have entered : , yBut the x 10 is never checked.Must I use two try except now ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] exceptions problem
Date: Fri, 10 Sep 2010 18:07:13 +0200 From: f...@libero.it To: tutor@python.org Subject: Re: [Tutor] exceptions problem Oops, I sent this to Roelof... Ok, I must amend it anyway... On 10/09/2010 17.13, Roelof Wobben wrote: ... def readposint(): x = raw_input(Please enter a positive integer :) try: x = int(x) and x 0 except: print x , is not a positive integer.Try again. return False return True y = readposint() print y while y == False: readposint() print You have entered : , y But the x 10 is never checked. Must I use two try except now ? Your first problem has nothing to do with exception handling. The culprit is Line 4: x = int(x) and x 0 I suppose that you forgot a second equal sign between x and int(x). If it were x == int(x) and x 0 it would have worked as expected. But this would not trigger any exception, if X is a number. So let's add one: if not (x == int(x) and x 0): raise(ValueError) Hope that helps, Roelof FrancescoHello Francesco,I change it to this :def readposint(): x = raw_input(Please enter a positive integer :) try: if not (x == int(x) and x 0): raise(ValueError) except: print x , is not a positive integer. Try again. return False return Truey = readposint() print y while y == False: readposint() print You have entered : , yBut -9 and 2 are both true.Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] exceptions problem
From: rwob...@hotmail.com To: tutor@python.org Date: Fri, 10 Sep 2010 16:12:08 + Subject: Re: [Tutor] exceptions problem Date: Fri, 10 Sep 2010 18:07:13 +0200 From: f...@libero.it To: tutor@python.org Subject: Re: [Tutor] exceptions problem Oops, I sent this to Roelof... Ok, I must amend it anyway... On 10/09/2010 17.13, Roelof Wobben wrote: ... def readposint(): x = raw_input(Please enter a positive integer :) try: x = int(x) and x 0 except: print x , is not a positive integer.Try again. return False return True y = readposint() print y while y == False: readposint() print You have entered : , y But the x 10 is never checked. Must I use two try except now ? Your first problem has nothing to do with exception handling. The culprit is Line 4: x = int(x) and x 0 I suppose that you forgot a second equal sign between x and int(x). If it were x == int(x) and x 0 it would have worked as expected. But this would not trigger any exception, if X is a number. So let's add one: if not (x == int(x) and x 0): raise(ValueError) Hope that helps, Roelof FrancescoHello Francesco,I change it to this :def readposint(): x = raw_input(Please enter a positive integer :) try: if not (x == int(x) and x 0): raise(ValueError) except: print x , is not a positive integer. Try again. return False return Truey = readposint() print y while y == False: readposint() print You have entered : , yBut -9 and 2 are both true.RoelofBecause I want to understand why this happens I wrote this test programm :def readposint(): x = raw_input(Please enter a positive integer :) print x if x == int(x) : print 01-True else: print 01-False print int(x) if x 0 : print 02-True else: print 02-False return y = readposint() print y while y == False: readposint() print You have entered : , y But I see wierd output :When x = 3 I get this output :Please enter a positive integer :3301-False302-TrueNoneYou have entered : None That's wierd. 3 is a integer so 01 must be True and 3 is bigger then 0 so that one must be false. Can someone explain me why this happens ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] exceptions problem
Date: Fri, 10 Sep 2010 20:23:09 +0200 From: f...@libero.it To: tutor@python.org Subject: Re: [Tutor] exceptions problem On 10/09/2010 18.12, Roelof Wobben wrote: ... def readposint(): x = raw_input(Please enter a positive integer :) try: if not (x == int(x) and x 0): raise(ValueError) except: print x , is not a positive integer.Try again. return False return True y = readposint() print y while y == False: readposint() print You have entered : , y But -9 and 2 are both true. My fault, I didn't notice that after raw_input, whatever you enter is a STRING, not an integer! So, without any exception thrown, the comparison x == int(x) is always False. Let's make it better: if (int(x)0 or (float(x) - int(x) 0)): raise(ValueError) Then, if the input value x is indeed a positive integer, you should return x, not True or False. Try returning -1 if the exception is thrown, in line 7, and returning x in line 8. Then, you should change also line 12... ok, here's to you: def readposint(): x = raw_input(Please enter a positive integer :) try: if (int(x)0 or (float(x) - int(x) 0)): raise(ValueError) except: print x , is not a positive integer.Try again. return -1 return x y = readposint() print y while y == -1: readposint() print You have entered : , y Roelof FrancescoThank you.I never thought that you can use a float and a integer to look if the number is a integer.Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] recursive problem
Hello, I have this : def recursive_count(target, nested_num_list): recursive_count(2, [2, 9, [2, 1, 13, 2], 8, [2, 6]]) 4 recursive_count(7, [[9, [7, 1, 13, 2], 8], [7, 6]]) 2 recursive_count(15, [[9, [7, 1, 13, 2], 8], [2, 6]]) 0 recursive_count(5, [[5, [5, [1, 5], 5], 5], [5, 6]]) 6 for element in nested_num_list: if type(element) == type([]): test = recursive_count(target, element) print element, target if element == target : count = count + 1 return count if __name__ == __main__: import doctest doctest.testmod() Now I get this message : UnboundLocalError: local variable 'count' referenced before assignment But if I do this : def recursive_count(target, nested_num_list): recursive_count(2, [2, 9, [2, 1, 13, 2], 8, [2, 6]]) 4 recursive_count(7, [[9, [7, 1, 13, 2], 8], [7, 6]]) 2 recursive_count(15, [[9, [7, 1, 13, 2], 8], [2, 6]]) 0 recursive_count(5, [[5, [5, [1, 5], 5], 5], [5, 6]]) 6 count = 0 for element in nested_num_list: if type(element) == type([]): test = recursive_count(target, element) print element, target if element == target : count = count + 1 return count if __name__ == __main__: import doctest doctest.testmod() The count will always be 0 if a nested list is being found. What's the python way to solve this Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] recursive problem
From: anand.shash...@gmail.com Date: Thu, 9 Sep 2010 15:08:10 +0530 Subject: Re: [Tutor] recursive problem To: rwob...@hotmail.com CC: tutor@python.org On Thu, Sep 9, 2010 at 2:21 PM, Roelof Wobben rwob...@hotmail.com wrote: Hello, I have this : def recursive_count(target, nested_num_list): recursive_count(2, [2, 9, [2, 1, 13, 2], 8, [2, 6]]) 4 recursive_count(7, [[9, [7, 1, 13, 2], 8], [7, 6]]) 2 recursive_count(15, [[9, [7, 1, 13, 2], 8], [2, 6]]) 0 recursive_count(5, [[5, [5, [1, 5], 5], 5], [5, 6]]) 6 for element in nested_num_list: if type(element) == type([]): test = recursive_count(target, element) print element, target if element == target : count = count + 1 return count if __name__ == __main__: import doctest doctest.testmod() Now I get this message : UnboundLocalError: local variable 'count' referenced before assignment It is because you are doing count = count + 1 But where is count defined. But if I do this : def recursive_count(target, nested_num_list): recursive_count(2, [2, 9, [2, 1, 13, 2], 8, [2, 6]]) 4 recursive_count(7, [[9, [7, 1, 13, 2], 8], [7, 6]]) 2 recursive_count(15, [[9, [7, 1, 13, 2], 8], [2, 6]]) 0 recursive_count(5, [[5, [5, [1, 5], 5], 5], [5, 6]]) 6 count = 0 for element in nested_num_list: if type(element) == type([]): test = recursive_count(target, element) print element, target if element == target : count = count + 1 return count if __name__ == __main__: import doctest doctest.testmod() The count will always be 0 if a nested list is being found. What's the python way to solve this I am not sure what do you want to achieve by this ? What is the problem statement ? The problem statement is that I must count how many times the target is in the nested_list. So I thougt that every nested list the function is called again so this list is also iterated. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] sort problem
Hello, I have this : def sort_sequence(seq): sort_sequence([3, 4, 6, 7, 8, 2]) [2, 3, 4, 6, 7, 8] sort_sequence((3, 4, 6, 7, 8, 2)) (2, 3, 4, 6, 7, 8) sort_sequence(nothappy) 'ahnoppty' if type(seq) == type([]): seq.sort() elif type(seq)== type(()): seq = tuple(sorted(seq)) else: seq2 = list(seq) seq2.sort() print seq2 seq.join(seq2) return seq The problem is that if I want to sort the characters in a string, the list exist of the sorted characters but as soon as I convert them to a string I get the old string. What went wrong ? Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sort problem
Subject: Re: [Tutor] sort problem From: evert@gmail.com Date: Wed, 8 Sep 2010 17:26:58 +0200 CC: tutor@python.org To: rwob...@hotmail.com I have this : def sort_sequence(seq): sort_sequence([3, 4, 6, 7, 8, 2]) [2, 3, 4, 6, 7, 8] sort_sequence((3, 4, 6, 7, 8, 2)) (2, 3, 4, 6, 7, 8) sort_sequence(nothappy) 'ahnoppty' if type(seq) == type([]): seq.sort() elif type(seq)== type(()): seq = tuple(sorted(seq)) else: seq2 = list(seq) seq2.sort() print seq2 seq.join(seq2) return seq The problem is that if I want to sort the characters in a string, the list exist of the sorted characters but as soon as I convert them to a string I get the old string. Carefully read the documentation for str.join: http://docs.python.org/library/stdtypes.html#str.join How does it work, what does it return, etc. Then fix the corresponding line in your code. As a hint: str.join does work quite different than list.sort; I assume you're confusing their syntaxes. Good luck, Evert str.join(iterable)¶ How it works. It puts all the elements of iterable into one string named str. So it returns a string. Str is here seq and the iterable is the list made by list.sort so seq2 So I don't see the error in that line. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sort problem
Date: Wed, 8 Sep 2010 12:38:03 -0400 From: gregb...@gmail.com To: tutor@python.org Subject: Re: [Tutor] sort problem On Wed, Sep 8, 2010 at 11:50 AM, Roelof Wobben rwob...@hotmail.com wrote: Subject: Re: [Tutor] sort problem From: evert@gmail.com Date: Wed, 8 Sep 2010 17:26:58 +0200 CC: tutor@python.org To: rwob...@hotmail.com I have this : def sort_sequence(seq): sort_sequence([3, 4, 6, 7, 8, 2]) [2, 3, 4, 6, 7, 8] sort_sequence((3, 4, 6, 7, 8, 2)) (2, 3, 4, 6, 7, 8) sort_sequence(nothappy) 'ahnoppty' if type(seq) == type([]): seq.sort() elif type(seq)== type(()): seq = tuple(sorted(seq)) else: seq2 = list(seq) seq2.sort() print seq2 seq.join(seq2) return seq The problem is that if I want to sort the characters in a string, the list exist of the sorted characters but as soon as I convert them to a string I get the old string. Carefully read the documentation for str.join: http://docs.python.org/library/stdtypes.html#str.join How does it work, what does it return, etc. Then fix the corresponding line in your code. As a hint: str.join does work quite different than list.sort; I assume you're confusing their syntaxes. Good luck, Evert str.join(iterable)¶ How it works. It puts all the elements of iterable into one string named str. So it returns a string. Str is here seq and the iterable is the list made by list.sort so seq2 So I don't see the error in that line. Roelof The error is that you misunderstand the usage of str.join. It doesn't do it in place, i.e. it doesn't change the actual string, so you have to have a variable to capture the response. The biggest thing, though, is that in str.join, str is not the string to store the joined iterator in, it's the separator for the string. so, in your case, where you have seq.join(seq2) You really want seq = .join(seq2) where is the separator to join seq2 on (an empty string in this case) HTH. -- Greg Bair gregb...@gmail.com Oke, If I understand it right with join I can put two strings into 1 string. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sort problem
Date: Wed, 8 Sep 2010 20:10:28 +0200 From: f...@libero.it To: tutor@python.org Subject: Re: [Tutor] sort problem On 08/09/2010 19.12, Francesco Loffredo wrote: ... a little example: separator = Roelof list = [Wobben, Python, Learner] print separator.join(list) ... what you will get? Guess before you try. There's more, I forgot to add: print separator This is important, this method *returns* a *NEW* string, it does not modify the providing string (here separator)! This means you must save the result somewhere, if you want to use it later: together = separator.join(list) Francesco ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Oke, I now see what everyone try to teach me. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] exercise correct ??
Hello, Oke, the 4 is a starting point for the index. Next problem. The begin looks like this : index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4) But in the module I get this result : val = 5 seq = (1, 2, 4, 5, 6, 10, 5, 5 So the 4 is not avaible anymore. Now I can change the header to index(val, seq, start=0) to index (val, seq, start) But I think that's not what the exercise wants. Is there another way I can use the 4 ? Roelof To: tutor@python.org From: alan.ga...@btinternet.com Date: Mon, 6 Sep 2010 23:28:22 +0100 Subject: Re: [Tutor] exercise correct ?? Roelof Wobben rwob...@hotmail.com wrote # def index_of(val, seq, start=0): index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4) 6 But I get this message : Failed example: index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4) Expected: 6 Got: 3 # But in that tuple 5 is on position 3. Is the exercise here wrong ? No because the start position is 4 so you don;t see the 5 in position 3. HTH, -- Alan Gauld Author of the Learn to Program web site http://www.alan-g.me.uk/ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] exercise correct ??
Date: Tue, 7 Sep 2010 00:52:38 -0700
From: alan.ga...@btinternet.com
Subject: Re: [Tutor] exercise correct ??
To: rwob...@hotmail.com; tutor@python.org
Oke, the 4 is a starting point for the index.
Next problem.
The begin looks like this :
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
But in the module I get this result :
val = 5
seq = (1, 2, 4, 5, 6, 10, 5, 5
So the 4 is not avaible anymore.
Yes it is. It is the start parameter.
The function definition is
def index_of(val, seq, start=0):
val is the first value, 5, seq is the tuple and start is 4.
Now I can change the header to index(val, seq, start=0) to index (val, seq,
start)
But I think that's not what the exercise wants.
Why would you want to do that? It would force you to provide a start value
for every call. The point of having a default value (=0) is so that you do not
need to specify start every time you use the function. But eveb if you do not
use the start value it will still have a value, 0.
There is no difference, you can access it exactly like the other parameters.
Just use its name.
HTH,
Alan G.
Oke,
Then this is the solution :
def index_of(val, seq, start=0):
index_of(9, [1, 7, 11, 9, 10])
3
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5))
3
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
6
index_of('y', 'happy birthday')
4
index_of('banana', ['apple', 'banana', 'cherry', 'date'])
1
index_of(5, [2, 3, 4])
-1
index_of('b', ['apple', 'banana', 'cherry', 'date'])
-1
try:
plek = seq.index(val, start)
except:
plek = -1
return plek
Roelof
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[Tutor] why do i get None as output
Hello,
I have this programm:
def encapsulate(val, seq):
if type(seq) == type():
return str(val)
if type(seq) == type([]):
return [val]
return (val,)
def insert_in_middle(val, seq):
middle = len(seq)/2
return seq[:middle] + encapsulate(val, seq) + seq[middle:]
def make_empty(seq):
make_empty([1, 2, 3, 4])
[]
make_empty(('a', 'b', 'c'))
()
make_empty(No, not me!)
''
word2=
teller=0
if type(seq) == type([]):
teller=0
while teller len(seq):
seq[teller]=
teller = teller + 1
elif type(seq) == type(()):
tup2 = list (seq)
while teller tup2.len():
tup2[teller]=
teller = teller + 1
seq = tuple(tup2)
else:
seq =
test = make_empty([1, 2, 3, 4])
print test
But now I get None as output instead of []
Can anyone explain why that happens ?
Roelof
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Re: [Tutor] why do i get None as output
To: tutor@python.org
From: alan.ga...@btinternet.com
Date: Mon, 6 Sep 2010 08:27:31 +0100
Subject: Re: [Tutor] why do i get None as output
Roelof Wobben rwob...@hotmail.com wrote
def make_empty(seq):
word2=
teller=0
if type(seq) == type([]):
teller=0
while teller len(seq):
seq[teller]=
teller = teller + 1
elif type(seq) == type(()):
tup2 = list (seq)
while teller tup2.len():
tup2[teller]=
teller = teller + 1
seq = tuple(tup2)
else:
seq =
test = make_empty([1, 2, 3, 4])
But now I get None as output instead of []
Because None is the default return value from a function.
If you do not return a value (which you don;t in this case) then
Python automatically returns None.
You need to return something from your make_empty function.
Also, if all you want to do is return an empty version of
whatever has been passed in there are much easier
ways of doing it! And in fact, a list of empty strings is
not the same as an empty list...
HTH
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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Oke,
I put a return seq in the programm and it looks now like this :
def encapsulate(val, seq):
if type(seq) == type():
return str(val)
if type(seq) == type([]):
return [val]
return (val,)
def insert_in_middle(val, seq):
middle = len(seq)/2
return seq[:middle] + encapsulate(val, seq) + seq[middle:]
def make_empty(seq):
make_empty([1, 2, 3, 4])
[]
make_empty(('a', 'b', 'c'))
()
make_empty(No, not me!)
''
if type(seq) == type([]):
seq = []
elif type(seq) == type(()):
seq=()
else:
seq =
return seq
if __name__ == __main__:
import doctest
doctest.testmod()
This works but I don't think its what the exercise means :
Create a module named seqtools.py. Add the functions encapsulate and
insert_in_middle from the chapter. Add doctests which test that these two
functions work as intended with all three sequence types.
Add each of the following functions to seqtools.py:
def make_empty(seq):
make_empty([1, 2, 3, 4])
[]
make_empty(('a', 'b', 'c'))
()
make_empty(No, not me!)
''
So i think I have to use encapsulate and insert_in_middle. And I don't use it.
Roelof
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[Tutor] exercise correct ??
Hello,
I have this programm :
def index_of(val, seq, start=0):
index_of(9, [1, 7, 11, 9, 10])
3
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5))
3
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
6
index_of('y', 'happy birthday')
4
index_of('banana', ['apple', 'banana', 'cherry', 'date'])
1
index_of(5, [2, 3, 4])
-1
index_of('b', ['apple', 'banana', 'cherry', 'date'])
-1
plek = 0
if type(seq) == type([]):
plek = seq.index(val)
elif type(seq) == type(()):
seq = list (seq)
plek = seq.index(val)
else :
plek = seq.find(val)
return plek
But I get this message :
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 70, in
__main__.index_of
Failed example:
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
Expected:
6
Got:
3
But in that tuple 5 is on position 3.
Is the exercise here wrong ?
Roelof
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Re: [Tutor] exercise correct ??
Date: Mon, 6 Sep 2010 21:45:17 +0200
Subject: Re: [Tutor] exercise correct ??
From: sander.swe...@gmail.com
To: rwob...@hotmail.com
CC: tutor@python.org
On 6 September 2010 19:32, Roelof Wobben rwob...@hotmail.com wrote:
def index_of(val, seq, start=0):
index_of(9, [1, 7, 11, 9, 10])
3
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5))
3
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
6
index_of('y', 'happy birthday')
4
index_of('banana', ['apple', 'banana', 'cherry', 'date'])
1
index_of(5, [2, 3, 4])
-1
index_of('b', ['apple', 'banana', 'cherry', 'date'])
-1
plek = 0
if type(seq) == type([]):
plek = seq.index(val)
elif type(seq) == type(()):
seq = list (seq)
plek = seq.index(val)
else :
plek = seq.find(val)
return plek
Not sure if this is correct but why don't you check for the index
attribute? It is part of both lists and strings. Also you can use
try/except to catch a ValueError. My version below, but I dislike the
list() usage...
def index_of(val, seq, start=0):
if hasattr(seq, 'index'):
try:
return seq.index(val, start)
except ValueError:
return -1
else:
try:
return list(seq).index(val, start)
except ValueError:
return -1
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 70, in
__main__.index_of
Failed example:
index_of(5, (1, 2, 4, 5, 6, 10, 5, 5), 4)
Expected:
6
Got:
3
But in that tuple 5 is on position 3.
Is the exercise here wrong ?
Looks like it, or it's a typo.
Greets
Sander
Hello Sander,
I agree that index is a part of string and list.
But not a part of a tuple.
As far as I know index is not a part of tuple so I have to convert it to a list
so I can use index.
Roelof
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[Tutor] (no subject)
Hello,
I have made this program as solution to a exercise from thinking like a
computer scientist.
def encapsulate(val, seq):
if type(seq) == type():
return str(val)
if type(seq) == type([]):
return [val]
return (val,)
def insert_in_middle(val, seq):
middle = len(seq)/2
return seq[:middle] + encapsulate(val, seq) + seq[middle:]
def make_empty(seq):
make_empty([1, 2, 3, 4])
[]
make_empty(('a', 'b', 'c'))
()
make_empty(No, not me!)
''
if type(element) == type([]):
for word2 in seq :
word2 =
elif type(element) == type(()):
tup2 = list (seq)
while teller tup2.len():
tup2[teller]=
teller = teller + 1
seq = tuple(tup2)
else:
seq =
test = make_empty([1, 2, 3, 4])
print test
But now Im getting this error message :
Traceback (most recent call last):
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 33, in module
test = make_empty([1, 2, 3, 4])
File C:\Users\wobben\workspace\oefeningen\src\test.py, line 21, in make_empty
if type(element) == type([]):
NameError: global name 'element' is not defined
What went wrong here ?
Roelof
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Re: [Tutor] (no subject)
From: st...@pearwood.info To: tutor@python.org Date: Sun, 5 Sep 2010 23:55:32 +1000 Subject: Re: [Tutor] (no subject) On Sun, 5 Sep 2010 11:44:09 pm Roelof Wobben wrote: Hello, I have made this program as solution to a exercise from thinking like a computer scientist. [...] But now Im getting this error message : Traceback (most recent call last): File C:\Users\wobben\workspace\oefeningen\src\test.py, line 33, in module test = make_empty([1, 2, 3, 4]) File C:\Users\wobben\workspace\oefeningen\src\test.py, line 21, in make_empty if type(element) == type([]): NameError: global name 'element' is not defined What went wrong here ? Read the error message again: NameError: global name 'element' is not defined You are trying to use something called element, but you haven't created anything with that name. The error message even tells you were the problem is: line 21, in the function make_empty. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor Hello Steven. I understand the error message. I follow this example in the book : http://openbookproject.net/thinkcs/python/english2e/ch11.html And there element is not defined. Roelof ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] can this be done easerly
Hello,
For a exerise I made this one :
import string
def extract_words(s):
extract_words('Now is the time! Now, is the time? Yes, now.')
['now', 'is', 'the', 'time', 'now', 'is', 'the', 'time', 'yes', 'now']
extract_words('she tried to curtsey as she spoke--fancy')
['she', 'tried', 'to', 'curtsey', 'as', 'she', 'spoke', 'fancy']
word=
s=string.lower(s)
for char in s :
if ord(char) =65 and ord(char) = 122 or ord(char)==32 or
ord(char)==45:
word= word + char
word=string.split(word, --)
word=string.join(word, )
word=word.replace ( , )
word=string.split(word, )
return word
if __name__ == '__main__':
import doctest
doctest.testmod()
But now I wonder if this can be done more easerly ?
Roelof
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