Re: [Tutor] system()? popen2()? How to execute a command save its output?
You might also consider pexpect. http://pexpect.sourceforge.net/ It's designed for interactive console applications like ftp. For popen() style access, the recommended approach is the subprocess module. You should be able to find an example in the docs to fit your application. http://docs.python.org/library/subprocess.html Cheers On Wednesday 29 September 2010, James Hartley wrote: I'm needing to transfer the following shell construct to Python, plus save the output of execution: FTP_SITE='ftp.somesite.com' ftp -a $FTP_SITE EOF binary prompt off cd /some_dir dir bye EOF Here, the FTP client accepts commands from STDIN, so all commands are saved in a temporary file which is redirected to the client application. I also need to save whatever output is generated. How can this be done in Python? Thanks. Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] function error
On Wed, Sep 29, 2010 at 11:13 PM, Alan Gauld alan.ga...@btinternet.com wrote: OK, Thats a non standard error trace so presumably you are running it inside an IDE of some kind? It may be the IDE is masking the true error. What happens if you just execute the code from a shell prompt in a console window? Can you send the error trace from that? yes, the IDE is ipython2.5 for debian; the call to the function is: randomMove2(10,30,15,90) but i don't know how to call it from the bash prompt correctly, can you point me to that ? -- roberto ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] system()? popen2()? How to execute a command save itsoutput?
James Hartley jjhart...@gmail.com wrote I'm needing to transfer the following shell construct to Python, plus save the output of execution: Are you sure? It looks like you would be better writing a python program using the ftp module. Shells are intended to execute external programs but Python provides the tools to do the job directly from Python, with no need to start external programs in most cases. FTP_SITE='ftp.somesite.com' ftp -a $FTP_SITE EOF binary prompt off cd /some_dir dir bye EOF If you really really need to use an external process use the subprocess module. But first check that you can't do it from within Python. 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
Re: [Tutor] __import__()
On Thu, Sep 23, 2010 at 5:26 PM, Pete pkoe...@xs4all.nl wrote:
Hiya,
still working on my plugin architecture. I figured out how to import
modules of which I don't know the name yet at compile time,
by using __import__() instead of import.
So that works fine when I want to have the equivalent of
import spam
... by using
__import__('spam')
Question:
what is the equivalent of
from spam import *
may be
function = getattr(spam, function_name)
J.
?
thanks,
Pete
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Re: [Tutor] system()? popen2()? How to execute a command save its output?
Hi, I've once written a script to sync my website with a local directory. I guess that you will find anything you need in the FTPHelper class. Have a look at: http://home.arcor.de/ralf_schoenian/websync/index.html At the bottom of the page you can view and download the script. Any questions are welcome. Ralf James Hartley jjhart...@gmail.com hat am 30. September 2010 um 06:29 geschrieben: I'm needing to transfer the following shell construct to Python, plus save the output of execution: FTP_SITE='ftp.somesite.com [http://ftp.somesite.com] ' ftp -a $FTP_SITE EOF binary prompt off cd /some_dir dir bye EOF Here, the FTP client accepts commands from STDIN, so all commands are saved in a temporary file which is redirected to the client application. I also need to save whatever output is generated. How can this be done in Python? Thanks. Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] generating independent random numbers
On Thu, 30 Sep 2010 02:38:31 pm Dave Angel wrote: [snip nearly 300 lines of quoted text and 7 lines of new content] Dave, and Carter, are the delete and backspace keys on your keyboards broken? There's no need to quote the ENTIRE thread every time you reply, and then quote it in full AGAIN a handful of minutes later. Please trim your quoting to only show the relevant parts of the email that you are actually replying to, or to show context. Nobody wants to have to scroll past pages upon pages of quoted text that we've already read four or five times to get to your reply. Thank you. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] function error
Copy the code into a text file with a name ending in .py - lets call it myfile.py for now (if you have not already done so) From a bash prompt type $ python myfile.py Then cut n paste any error messages into an email to the list Alan Gauld Author of the Learn To Program website http://www.alan-g.me.uk/ - Original Message From: roberto robert...@gmail.com To: Alan Gauld alan.ga...@btinternet.com Cc: tutor@python.org Sent: Thursday, 30 September, 2010 10:02:51 Subject: Re: [Tutor] function error On Wed, Sep 29, 2010 at 11:13 PM, Alan Gauld alan.ga...@btinternet.com wrote: OK, Thats a non standard error trace so presumably you are running it inside an IDE of some kind? It may be the IDE is masking the true error. What happens if you just execute the code from a shell prompt in a console window? Can you send the error trace from that? yes, the IDE is ipython2.5 for debian; the call to the function is: randomMove2(10,30,15,90) but i don't know how to call it from the bash prompt correctly, can you point me to that ? -- roberto ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Printing prime numbers
Hi all, I am trying to write a function that prints out which number is prime in range (1,500) The function would check thru and the print out something like 1 is prime 2 is prime 3 is prime 4 is not 5 is prime Please help me. Thank you. Sent from my BlackBerry wireless device from MTN ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Printing prime numbers
On Thu, Sep 30, 2010 at 5:27 PM, delegb...@dudupay.com wrote: Hi all, I am trying to write a function that prints out which number is prime in range (1,500) The function would check thru and the print out something like 1 is prime 2 is prime 3 is prime 4 is not 5 is prime Please help me. Thank you. Can you show us your attempts. We may try to help where you did wrong. Sent from my BlackBerry wireless device from MTN ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor -- ~l0nwlf ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Printing prime numbers
Ok. I will do that as soon As I get back to my workstation. Sent from my BlackBerry wireless device from MTN -Original Message- From: Shashwat Anand anand.shash...@gmail.com Date: Thu, 30 Sep 2010 19:11:33 To: delegb...@dudupay.com Cc: tutor@python.org Subject: Re: [Tutor] Printing prime numbers On Thu, Sep 30, 2010 at 5:27 PM, delegb...@dudupay.com wrote: Hi all, I am trying to write a function that prints out which number is prime in range (1,500) The function would check thru and the print out something like 1 is prime 2 is prime 3 is prime 4 is not 5 is prime Please help me. Thank you. Can you show us your attempts. We may try to help where you did wrong. Sent from my BlackBerry wireless device from MTN ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor -- ~l0nwlf ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Printing prime numbers
On Thu, Sep 30, 2010 at 1:57 PM, delegb...@dudupay.com wrote: 1 is prime One is /not/ prime. /pedant ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] system()? popen2()? How to execute a command save itsoutput?
I'm needing to transfer the following shell construct to Python, plus save the output of execution: FTP_SITE='ftp.somesite.com' ftp -a $FTP_SITE EOF binary prompt off cd /some_dir dir bye EOF Are you sure? It looks like you would be better writing a python program using the ftp module. Shells are intended to execute external programs but Python provides the tools to do the job directly from Python, with no need to start external programs in most cases. NB: If you use the ftp module (which works great), be sure to open all files in Binary mode. Voice of experience here. Alan ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Doubly linked list
I was having trouble, where on the python site can i find steps on classes and making a doubly linked list, is there a help option for linked lists. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] system()? popen2()? How to execute a command save itsoutput?
On Thu, Sep 30, 2010 at 7:27 AM, R. Alan Monroe amon...@columbus.rr.comwrote: I'm needing to transfer the following shell construct to Python, plus save the output of execution: FTP_SITE='ftp.somesite.com' ftp -a $FTP_SITE EOF binary prompt off cd /some_dir dir bye EOF NB: If you use the ftp module (which works great), be sure to open all files in Binary mode. Voice of experience here. Thanks all, for the responses thus far. I was not aware of the ftplib module. This looks like it will take care of most of my needs. However, output from these FTP commands are sent to stdout. Is there a way to redirect/capture stdout, as I need to parse the directory listings? Thanks, again. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Runnig a windows.exe from python
Hello !
I apoligize for the format of my last message, I didn't realize that putting
my text in bold format will show those asterisks.
By the way you're Alan, for the pythom module I first had to read my
arguments and passed them to the os.system(), it worked. Now when I execute
this command, in my normal DOS Windows, I must change to another path before
I run the .exe, I don't know how to tell this to my python module. This is
my code:
from dbf import *
from osgeo import ogr
import os
import sys
def call():
os.chdir('C:\Python26')
arg1 = R1G-GEODESIA2.shp
arg2 = LAYER = 'R1G-GEODESIA'
arg4 = tapalpa_05_plani_point.shp
os.system('C:/Archivos de programa/FWTools2.4.7/setfw')
os.system('C:/Archivos de programa/FWTools2.4.7/bin/ogr2ogr.exe'+
+arg1 + + -where + + arg3 + +arg4)
call()
If I run it, it shows me the following error:
Python 2.6.6 (r266:84297, Aug 24 2010, 18:46:32) [MSC v.1500 32 bit (Intel)]
on
win32
Type help, copyright, credits or license for more information.
import fw
Ingresa el nombre para el nuevo mapa
R1G-GEODESIA2.shp
Ingresa la condicion
LAYER = 'R1G-GEODESIA'
Ingresa el nombre del mapa original
tapalpa_05_plani_point.shp
FAILURE:
Unable to open datasource `arg3' with the following drivers.
- ESRI Shapefile
- MapInfo File
- UK .NTF
- SDTS
- TIGER
- S57
- DGN
- VRT
- REC
- Memory
- BNA
- CSV
- NAS
- GML
- GPX
- KML
- GeoJSON
- Interlis 1
- Interlis 2
- GMT
- SQLite
- ODBC
- PGeo
- OGDI
- PostgreSQL
- MySQL
- XPlane
- AVCBin
- AVCE00
- DXF
- Geoconcept
- GeoRSS
- GPSTrackMaker
- VFK
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[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
Re: [Tutor] inheritance problem
Hi Roelof, Im following this page : http://openbookproject.net/thinkcs/python/english2e/ch17.html I just checked this, and it appears you've copied this example fine. snip / 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 snip / 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. The error message tells you exactly what is wrong: there is no 'pop' attribute. Or in this case, rather there is no pop() method for the class Deck. You're calling it as self.pop() within Deck, hence Deck should provide a pop method (the self refers to any instance of Deck that you're currently using). But pop() is nowhere defined... Now, the commentary in the exercise says a card is removed from the deck using the list method pop, which would suggest self is of type(list). Since self is also of type(Deck), Deck should inherit from list: class Deck(list). Thus, in my view, the example is broken, and simply not well tested. Hence I said you copied it fine, and nothing went wrong there. Seen the rest of the example, I actually suspect that inheriting from standard Python types is not yet discussed here, and will be done later. So inheriting from list is one option, but may not be right in the context of this exercise. Writing your own pop() method for Deck is another option. And, since this is an openbookproject, I would expect that means you can edit it yourself. That doesn't appear to be directly the case, but you could at least notify the authors (bottom of page) and let them know that you think this example is broken (feel free to refer them to this thread in the mailing list). Unless of course, there was some example done before this chapter that provided a pop() method. Evert ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] inheritance problem
Sorry I hit the send button instead of the save button On Thu, Sep 30, 2010 at 2:58 PM, Bob Gailer bgai...@gmail.com wrote: On Thu, Sep 30, 2010 at 2:38 PM, Roelof Wobben rwob...@hotmail.com wrote: hello, Im following this page : http://openbookproject.net/thinkcs/python/english2e/ch17.html [snip] What went wrong here. IMHO you are tackling a very large program while still not getting Python basics and still not walking through the program I once again am weary of holding your hand. I suggest (again) that you walk through the program BY HAND step by step, analyzing and understanding what happens at each step. There are so many problems in your code even if I told you exactly what's wrong you will just get the next error-or-unexpected result then the next, and so on. I will start you: game = CardGame() # leads to class CardGame: def __init__(self): self.deck = Deck() #leads to class Deck: def __init__(self): self.cards = [] # an empty list is bound to the instance attribute cards for suit in range(4): for rank in range(1, 14): self.cards.append(Card(suit, rank)) # one-by-one Card instances are appended to self.cards #leads to class Card: suits = [Clubs, Diamonds, Hearts, Spades] # a list of suit names is bound to class attribute suits ranks = [narf, Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King] # a list of rank names is bound to class attribute ranks def __init__(self, suit=0, rank=0): self.suit = suit # the suit number passed as an argument is bound to the Card instance suit self.rank = rank # the rank number passed as an argument is bound to the Card instance rank # the result is a Card instance with two attributes, suit and rank. And so forth. Laborious? Time consuming? Lots of detail? Yes. Most of us have gone thru the same thing in our education. Regarding the error: AttributeError: Deck instance has no attribute 'pop' You should be able by now to know what that means and why it is happening. A lot of us on this list are spending a lot of time helping you. I for one again am imploring you to spend more time gaining understanding and asking us for less help of this nature. Others may disagree - that is my opinion. -- Bob Gailer 919-636-4239 ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Doubly linked list
On 9/30/2010 6:24 AM T MURPHY said... I was having trouble, where on the python site can i find steps on classes and making a doubly linked list, is there a help option for linked lists. Python itself doesn't provide a doubly linked list so I wouldn't expect to find support ifo on the python site therefore, but google yields multiple hits some of which appear to provide working classes providing doubly linked lists. See for example http://bytes.com/topic/python/answers/523772-how-implement-linked-list-python but if you're new to python but not to programming you'll find a lot of useful info working the tutorial. HTH, Emile ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] (de)serialization questions
Hi,
I have data about zip codes, street and city names (and perhaps later also of
street numbers). I made a dictionary of the form {zipcode: (street, city)}
I dumped the dictionary into a marshal file. I have two questions:
The first question is a very basic one: if I deserialize the dictionary it is
placed into memory. This is fast, but can cause problems for very large
objects.
Are there forms of object permanence that do not read all data into memory?
Does
the shelve module work this way?
Second, does anybody know of a speed comparison test (e.g., web source) of
various de/serialization methods? I don't mind if the dumping is somewhat slow.
Fast loading speed is more important for my purpose.
Btw, I am aware of the portability problems of marshal files. I found that,
compared to a shelve object, dumping is *much* faster, loading is slightly
faster, look-ups are scarily fast, and file size is about half.
I am using Python 2.5 and installing non-standard modules is a problem for the
IT droids in my office.
Cheers!!
Albert-Jan
~~
All right, but apart from the sanitation, the medicine, education, wine, public
order, irrigation, roads, a fresh water system, and public health, what have
the
Romans ever done for us?
~~
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Re: [Tutor] inheritance problem
And so forth. Laborious? Time consuming? Lots of detail? Yes. Most of us have gone thru the same thing in our education. --- You forgot: 'Lots of frowning', 'lots of sixpacks' and 'lots of FUN' ;-))) Cheers!! Albert-Jan ~~ All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us? ~~ From: Bob Gailer bgai...@gmail.com To: Roelof Wobben rwob...@hotmail.com; tutor@python.org Sent: Thu, September 30, 2010 9:12:48 PM Subject: Re: [Tutor] inheritance problem Sorry I hit the send button instead of the save button On Thu, Sep 30, 2010 at 2:58 PM, Bob Gailer bgai...@gmail.com wrote: On Thu, Sep 30, 2010 at 2:38 PM, Roelof Wobben rwob...@hotmail.com wrote: hello, Im following this page : http://openbookproject.net/thinkcs/python/english2e/ch17.html [snip] What went wrong here. IMHO you are tackling a very large program while still not getting Python basics and still not walking through the program I once again am weary of holding your hand. I suggest (again) that you walk through the program BY HAND step by step, analyzing and understanding what happens at each step. There are so many problems in your code even if I told you exactly what's wrong you will just get the next error-or-unexpected result then the next, and so on. I will start you: game = CardGame() # leads to class CardGame: def __init__(self): self.deck = Deck() #leads to class Deck: def __init__(self): self.cards = [] # an empty list is bound to the instance attribute cards for suit in range(4): for rank in range(1, 14): self.cards.append(Card(suit, rank)) # one-by-one Card instances are appended to self.cards #leads to class Card: suits = [Clubs, Diamonds, Hearts, Spades] # a list of suit names is bound to class attribute suits ranks = [narf, Ace, 2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King] # a list of rank names is bound to class attribute ranks def __init__(self, suit=0, rank=0): self.suit = suit # the suit number passed as an argument is bound to the Card instance suit self.rank = rank # the rank number passed as an argument is bound to the Card instance rank # the result is a Card instance with two attributes, suit and rank. And so forth. Laborious? Time consuming? Lots of detail? Yes. Most of us have gone thru the same thing in our education. Regarding the error: AttributeError: Deck instance has no attribute 'pop' You should be able by now to know what that means and why it is happening. A lot of us on this list are spending a lot of time helping you. I for one again am imploring you to spend more time gaining understanding and asking us for less help of this nature. Others may disagree - that is my opinion. -- Bob Gailer 919-636-4239 ___ 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] inheritance problem
I looked at the chapter before, and found this in particular: class Deck: def __init__(self): self.cards = [] for suit in range(4): for rank in range(1, 14): self.cards.append(Card(suit, rank)) I think the error in the book has to do with self.pop() instead should be self.cards.pop() Since cards are the items in the deck that get moved around, and since you are dealing at that line in your code that fails. -- Bob Gailer 919-636-4239 ___ Tutor maillist - tu...@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor -- Joel Goldstick ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Doubly linked list
T MURPHY t...@hotmail.com wrote I was having trouble, where on the python site can i find steps on classes and making a doubly linked list, is there a help option for linked lists. Thee are several sites that discuss list structures in Python, but mostly these are of academic interest only. Do you have a specific need for a doubly linked lists? They are very rarely required in Python because the standard list is sufficiently versatile for most purposes. 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] just what does read() return?
Hi all, I have a parser class which is supposed to take a text file and parse it. I will then do more with the resulting data. The file is in a particular format, specified by my professor, though this is not homework (it will be used to do homework later). The file is in the format: l vx vy z vx vy z where l is either D or U and x, y, and z are numbers. Anyway, I have the following lines: f=open(self.file, r) self.original=f.read() #I thought self.original would now be a string of all the data in self.file txt=str(self.original).split(r\n+) #create an array where elements are lines in file print txt I fully expected to see txt be an array of strings since I figured self.original would have been split on one or more new lines. It turns out, though, that I get this instead: ['l\nvx vy z\nvx vy z'] How is it that txt is not an array of the lines in the file, but instead still holds \n characters? I thought the manual said read() returns a string: To read a file's contents, call f.read(size), which reads some quantity of data and returns it as a string. size is an optional numeric argument. When size is omitted or negative, the entire contents of the file will be read and returned; it's your problem if the file is twice as large as your machine's memory. Otherwise, at most size bytes are read and returned. If the end of the file has been reached, f.read() will return an empty string ( ). I know I can use f.readline(), and I was doing that before and it all worked fine. However, I saw that I was reading the file twice and, in the interest of good practice if I ever have this sort of project with a huge file, I thought I would try to be more efficient and read it once. I will use self.original later again, so I need it either way, and I figured I could use it since I had already read the file to get it. TIA. -- Have a great day, Alex (msg sent from GMail website) mehg...@gmail.com; http://www.facebook.com/mehgcap ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] python Task
Kindly help me with the following tasks. You may want to start with explanations for me and then pseudo-codes, I should be able to take it from there. They are exercises from deitel how to program for Python. I have done a lot of thinking and its almost discouraging me. Please help. Thanks. 4.4 An integer greater than 1 is said to be prime if it is divisible by only 1 and itself. For example, 2, 3, 5 and 7 are prime numbers, but 4, 6, 8 and 9 are not. a) Write a function that determines whether a number is prime. b) Use this function in a program that determines and prints all the prime numbers between 2 and 1,000. c) Initially, you might think that n/2 is the upper limit for which you must test to see whether a number is prime, but you need go only as high as the square root of n. Rewrite the program and run it both ways to show that you get the same result. 4.5 An integer number is said to be a perfect number if the sum of its factors, including 1 (but not the number itself), is equal to the number. For example, 6 is a perfect number, because 6 = 1 + 2 + 3. Write a function perfect that determines whether parameter number is a perfect number. Use this function in a program that determines and prints all the perfect numbers between 1 and 1000. Print the factors of each perfect number to confirm that the number is indeed perfect. Challenge the power of your computer by testing numbers much larger than 1000. 4.7 Write a program that plays the game of “guess the number” as follows: Your program chooses the number to be guessed by selecting an integer at random in the range 1 to 1000. The program then displays I have a number between 1 and 1000. Can you guess my number? Please type your first guess. The player then types a first guess. The program responds with one of the following: 1. Excellent! You guessed the number! Would you like to play again (y or n)? 2. Too low. Try again. 3. Too high. Try again. If the player's guess is incorrect, your program should loop until the player finally gets the number right. Your program should keep telling the player Too high or Too low to help the player “zero in” on the correct answer. After a game ends, the program should prompt the user to enter y to play again or n to exit the game. 4.8 (Towers of Hanoi) Every budding computer scientist must grapple with certain classic problems. The Towers of Hanoi (see Fig. 4.23) is one of the most famous of these. Legend has it that, in a temple in the Far East, priests are attempting to move a stack of disks from one peg to another. The initial stack had 64 disks threaded onto one peg and arranged from bottom to top by decreasing size. The priests are attempting to move the stack from this peg to a second peg, under the constraints that exactly one disk is moved at a time and that at no time may a larger disk be placed above a smaller disk. A third peg is available for holding disks temporarily. Supposedly, the world will end when the priests complete their task, so there is little incentive for us to facilitate their efforts. Let us assume that the priests are attempting to move the disks from peg 1 to peg 3. We wish to develop an algorithm that will print the precise sequence of peg-to-peg disk transfers. If we were to approach this problem with conventional methods, we would rapidly find ourselves hopelessly knotted up in managing the disks. Instead, if we attack the problem with recursion in mind, it immediately becomes tractable. Moving n disks can be viewed in terms of moving only n - 1 disks (hence, the recursion), as follows: a) Move n - 1 disks from peg 1 to peg 2, using peg 3 as a temporary holding area. b) Move the last disk (the largest) from peg 1 to peg 3. c) Move the n - 1 disks from peg 2 to peg 3, using peg 1 as a temporary holding area. The process ends when the last task involves moving n = 1 disk, i.e., the base case. This is accomplished trivially by moving the disk without the need for a temporary holding area. Write a program to solve the Towers of Hanoi problem. Use a recursive function with four parameters: a) The number of disks to be moved b) The peg on which these disks are initially threaded c) The peg to which this stack of disks is to be moved d) The peg to be used as a temporary holding area Your program should print the precise instructions it will take to move the disks from the starting peg to the destination peg. For example, to move a stack of three disks from peg 1 to peg 3, your program should print the following series of moves: 1 → 3 (This means move one disk from peg 1 to peg 3.) 1 → 2 3 → 2 1 → 3 2 → 1 2→ 3 1→ 3 -- Sent from my mobile device Elegbede Muhammed Oladipupo OCA +2348077682428 +2347042171716 www.dudupay.com Mobile Banking Solutions | Transaction Processing | Enterprise Application Development ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] (de)serialization questions
I have data about zip codes, street and city names (and perhaps later also of
street numbers). I made a dictionary of the form {zipcode: (street, city)}
One dictionary with all of the data?
That does not seem like it will work. What happens when
2 addresses have the same zip code?
Are there forms of object permanence that do not read all data into memory?
How about a file?
You could write your data one record per line, and then
read it in one line at a time also.
You could also use a csv file, or maybe use a database
like sqlite.
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Re: [Tutor] just what does read() return?
On 9/30/10, Walter Prins wpr...@gmail.com wrote: On 30 September 2010 23:32, Alex Hall mehg...@gmail.com wrote: txt=str(self.original).split(r\n+) #create an array where elements OK, consider this Python shell session: s = line1\nline2 s.split() ['line1', 'line2'] s.split(r\n+) ['line1\nline2'] Hmm, so split doesn't like that seperator. Taking a step back -- It looks like you're trying to specify a regular expression as a split string. A string object's split method doesn't support regular expressions. The split function in the re module however does. Ah-ha!! re.split(r\n+, self.original) That did it, and my program once again runs as expected. Thanks! HTH Very much. Walter -- Have a great day, Alex (msg sent from GMail website) mehg...@gmail.com; http://www.facebook.com/mehgcap ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] just what does read() return?
On 30-Sep-10 15:49, Alex Hall wrote:
re.split(r\n+, self.original)
That did it, and my program once again runs as expected. Thanks!
If you don't need blank lines stripped out (r'\n+' considers multiple
consecutive \n characters to be a single record separator), you can
avoid the regex and just use the normal string split:
list_of_lines = giant_string.split('\n')
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[Tutor] Help - server health check reporter
Hey guys,
I’m trying to put together a script using urllib2, smtplib and
stripogram/html2text which will use a healthcheck url, read the response
after loading it and then email me the results without any unwanted html
tags. I was able to do that but, when I get a timeout on one of the servers
the script breaks with an error response. I’m very new to python and I don’t
know how to take that error and have it sent as well, instead of breaking
the script. Any advice or links I can check out that might be helpful? I
appreciate it.
I can include the python code if needed though at this point I'm sure it is
not very pythonic. {smile}
Regards,
-russ
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Re: [Tutor] Help - server health check reporter
On Fri, 1 Oct 2010 09:26:16 am Russell Smith wrote: I’m trying to put together a script using urllib2, smtplib and stripogram/html2text which will use a healthcheck url, read the response after loading it and then email me the results without any unwanted html tags. I was able to do that but, when I get a timeout on one of the servers the script breaks with an error response. Could you copy and paste the exact error message, including the full traceback? Also, what version of Python are you using? I’m very new to python and I don’t know how to take that error and have it sent as well, instead of breaking the script. Any advice or links I can check out that might be helpful? I appreciate it. try: code that times out goes here except Exception as error: do something with error Obviously this isn't exactly Python code, but I can be more specific once you've answered the above two questions. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] python Task
On Fri, 1 Oct 2010 08:38:31 am Dipo Elegbede wrote: 4.4 An integer greater than 1 is said to be prime if it is divisible by only 1 and itself. For example, 2, 3, 5 and 7 are prime numbers, but 4, 6, 8 and 9 are not. a) Write a function that determines whether a number is prime. The first thing you need to know is that you can find out the remainder after division by using the % operator. For example: 10 % 5 = 0 # 10 = 5*2 11 % 5 = 1 # 11 = 5*2 + 1 12 % 5 = 2 # 12 = 5*2 + 2 and so forth. So you can check whether a number is divisible by another with: if n % divisor == 0: print n is exactly divisible by divisor else: print n is not divisible by divisor So to find out whether a number n is prime, you need to check whether it is divisible by each whole number starting from 2: for divisor in range(2, n): if n is divisible by divisor then n is not prime # outside the loop print prime The above does a LOT of unnecessary work. Some improvements: * Once you've discovered that a number is not prime, you can exit the loop. * There's no need to test every number up to n-1. Think about what the greatest number you need to test would be. * If a number isn't divisible by 2, then it can't possibly be divisible by 4, 6, 8, 10, ... either. So apart from 2, there's no need to check even numbers. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] just what does read() return?
On Fri, 1 Oct 2010 08:49:31 am Alex Hall wrote:
Ah-ha!!
re.split(r\n+, self.original)
That did it, and my program once again runs as expected. Thanks!
There is no need to crack that tiny peanut with the 40 lb sledgehammer
of a regular expression.
list_of_lines = string.split('\n')
Much faster, simpler, and does the job. To get rid of empty lines:
list_of_lines = filter(None, string.split('\n'))
--
Steven D'Aprano
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Re: [Tutor] inheritance problem
Roelof Wobben rwob...@hotmail.com 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 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. The error tells you what is wrong, the Deck has no attribute called pop. Can you see a pop anywhere? So if the code you copied has an error how should it assign a card? Where are the cards stored? How would you get the first card from the collection? Does that work? 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. -- 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
Re: [Tutor] just what does read() return?
On Fri, 1 Oct 2010 08:32:40 am Alex Hall wrote: I fully expected to see txt be an array of strings since I figured self.original would have been split on one or more new lines. It turns out, though, that I get this instead: ['l\nvx vy z\nvx vy z'] There's no need to call str() on something that already is a string. Admittedly it doesn't do much harm, but it is confusing for the person reading, who may be fooled into thinking that perhaps the argument wasn't a string in the first place. The string split method doesn't interpret its argument as a regular expression. r'\n+' has no special meaning here. It's just three literal characters backslash, the letter n, and the plus sign. split() tries to split on that substring, and since your data doesn't include that combination anywhere, returns a list containing a single item: abcde.split(ZZZ) ['abcde'] How is it that txt is not an array of the lines in the file, but instead still holds \n characters? I thought the manual said read() returns a string: It does return a string. It is a string including the newline characters. [...] I know I can use f.readline(), and I was doing that before and it all worked fine. However, I saw that I was reading the file twice and, in the interest of good practice if I ever have this sort of project with a huge file, I thought I would try to be more efficient and read it once. You think that keeping a huge file in memory *all the time* is more efficient? It's the other way around -- when dealing with *small* files you can afford to keep it in memory. When dealing with huge files, you need to re-write your program to deal with the file a piece at a time. (This is often a good strategy for small files as well, but it is essential for huge ones.) Of course, small and huge is relative to the technology of the day. I remember when 1MB was huge. These days, huge would mean gigabytes. Small would be anything under a few tens of megabytes. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Runnig a windows.exe from python
On Fri, 1 Oct 2010 04:05:08 am Susana Iraiis Delgado Rodriguez wrote: Hello ! I apoligize for the format of my last message, I didn't realize that putting my text in bold format will show those asterisks. By the way you're Alan, for the pythom module I first had to read my arguments and passed them to the os.system(), it worked. Now when I execute this command, in my normal DOS Windows, I must change to another path before I run the .exe, I don't know how to tell this to my python module. os.chrdir(path) changes to a new path. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Doubly linked list
On Thu, 30 Sep 2010 11:24:06 pm T MURPHY wrote: I was having trouble, where on the python site can i find steps on classes Google is your friend: googling for python tutorial brings up lots of tutorials that will help. Here's the first one: http://docs.python.org/tutorial/ and making a doubly linked list, is there a help option for linked lists. Python doesn't supply a doubly-linked list, but it's easy to make your own. Here's a singly-linked list for you: class Node(object): def __init__(self, data, next=None): self.data = data self.next = next mylist = Node(a) mylist.next = Node(b, Node(c)) node = mylist while node is not None: print node.data node = node.next -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Printing prime numbers
On Thu, 30 Sep 2010 11:52:49 pm Emmanuel Ruellan wrote: On Thu, Sep 30, 2010 at 1:57 PM, delegb...@dudupay.com wrote: 1 is prime One is /not/ prime. /pedant There's no need to apologize for pedantry. Saying that one is prime is like saying that 2 is an odd number, or that glass is a type of meat. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] Mutable Properties
Dear Tutors,
I noticed that when you make a property to represent a mutable value
*class Obj(object):
def get(self):
print 'Get'
return self.prop
def set(self, new):
print 'Set'
self.prop = new
prop = property(get, set)
test = Obj()
test.prop = ['Hello']
*
and then try and use one of its methods.
*test.prop.append('World')
*It will treat it as a get, not a set.
*Output: Get
*Even thou you are basically changing its value.
*Before: ['Hello']
After: ['Hello', 'World']
*I know this happens because I'm not technically setting it to something
else, just getting one of its properties.
I was wondering how to make it fire off set to for certain methods.
Sincerely,
Me
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Re: [Tutor] Mutable Properties
On Fri, 1 Oct 2010 10:24:50 am Chris King wrote:
Dear Tutors,
I noticed that when you make a property to represent a mutable
value
*class Obj(object):
def get(self):
print 'Get'
return self.prop
def set(self, new):
print 'Set'
self.prop = new
prop = property(get, set)
test = Obj()
test.prop = ['Hello']
*
and then try and use one of its methods.
*test.prop.append('World')
*It will treat it as a get, not a set.
That's because it is a get. You get the property, and then you call one
of its methods. How could it be any different?
The object stored in the property could be anything. How can the class
know which methods modify it in place, and which ones don't?
test.prop.sort()
Did this modify the list or not?
*Output: Get
*Even thou you are basically changing its value.
But changing a mutable value means modifying it in place, not
re-assigning it. This is no different from:
mylist = test.prop # this is a get
mylist.append(something) # change it in place
Since there is no assignment to prop, there is no set.
*Before: ['Hello']
After: ['Hello', 'World']
*I know this happens because I'm not technically setting it to
something else, just getting one of its properties.
I was wondering how to make it fire off set to for certain methods.
You can't.
What problem are you trying to solve? There is likely another way to
solve it. (Not necessarily an easy way, but we'll see.)
--
Steven D'Aprano
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Re: [Tutor] Mutable Properties
On 9/30/2010 8:43 PM, Steven D'Aprano wrote:
On Fri, 1 Oct 2010 10:24:50 am Chris King wrote:
Dear Tutors,
I noticed that when you make a property to represent a mutable
value
*class Obj(object):
def get(self):
print 'Get'
return self.prop
def set(self, new):
print 'Set'
self.prop = new
prop = property(get, set)
test = Obj()
test.prop = ['Hello']
*
and then try and use one of its methods.
*test.prop.append('World')
*It will treat it as a get, not a set.
That's because it is a get. You get the property, and then you call one
of its methods. How could it be any different?
The object stored in the property could be anything. How can the class
know which methods modify it in place, and which ones don't?
test.prop.sort()
Did this modify the list or not?
*Output: Get
*Even thou you are basically changing its value.
But changing a mutable value means modifying it in place, not
re-assigning it. This is no different from:
mylist = test.prop # this is a get
mylist.append(something) # change it in place
Since there is no assignment to prop, there is no set.
*Before: ['Hello']
After: ['Hello', 'World']
*I know this happens because I'm not technically setting it to
something else, just getting one of its properties.
I was wondering how to make it fire off set to for certain methods.
You can't.
What problem are you trying to solve? There is likely another way to
solve it. (Not necessarily an easy way, but we'll see.)
So I'll have to create my own object which modifies each method to fire
off the set method if the old form and the new form are unequal, there
is no easy way?
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Re: [Tutor] just what does read() return?
On 9/30/10, Steven D'Aprano st...@pearwood.info wrote: On Fri, 1 Oct 2010 08:32:40 am Alex Hall wrote: I fully expected to see txt be an array of strings since I figured self.original would have been split on one or more new lines. It turns out, though, that I get this instead: ['l\nvx vy z\nvx vy z'] There's no need to call str() on something that already is a string. Admittedly it doesn't do much harm, but it is confusing for the person reading, who may be fooled into thinking that perhaps the argument wasn't a string in the first place. Agreed. I was having some (unrelated) trouble and was desperate enough to start forcing things to the data type I needed, just in case. The string split method doesn't interpret its argument as a regular expression. r'\n+' has no special meaning here. It's just three literal characters backslash, the letter n, and the plus sign. split() tries to split on that substring, and since your data doesn't include that combination anywhere, returns a list containing a single item: abcde.split(ZZZ) ['abcde'] Yes, that makes sense. How is it that txt is not an array of the lines in the file, but instead still holds \n characters? I thought the manual said read() returns a string: It does return a string. It is a string including the newline characters. [...] I know I can use f.readline(), and I was doing that before and it all worked fine. However, I saw that I was reading the file twice and, in the interest of good practice if I ever have this sort of project with a huge file, I thought I would try to be more efficient and read it once. You think that keeping a huge file in memory *all the time* is more efficient? Ah, I see what you mean now. I work with the data later, so you are saying that it would be better to just read the file as necessary, then then, when I need the file's data later, just read it again. It's the other way around -- when dealing with *small* files you can afford to keep it in memory. When dealing with huge files, you need to re-write your program to deal with the file a piece at a time. (This is often a good strategy for small files as well, but it is essential for huge ones.) Of course, small and huge is relative to the technology of the day. I remember when 1MB was huge. These days, huge would mean gigabytes. Small would be anything under a few tens of megabytes. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor -- Have a great day, Alex (msg sent from GMail website) mehg...@gmail.com; http://www.facebook.com/mehgcap ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Mutable Properties
On Fri, 1 Oct 2010 11:24:16 am Chris King wrote: What problem are you trying to solve? There is likely another way to solve it. (Not necessarily an easy way, but we'll see.) So I'll have to create my own object which modifies each method to fire off the set method if the old form and the new form are unequal, there is no easy way? I repeat... what problem are you trying to solve? Calling the set method for something that *doesn't* set a property doesn't sound like a solution to a problem to me. It sounds like a problem itself. -- Steven D'Aprano ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Mutable Properties
On 2:59 PM, Chris King wrote: On 9/30/2010 8:43 PM, Steven D'Aprano wrote: snip What problem are you trying to solve? There is likely another way to solve it. (Not necessarily an easy way, but we'll see.) So I'll have to create my own object which modifies each method to fire off the set method if the old form and the new form are unequal, there is no easy way? Try rephrasing that in English. Or just answer Chris's question. What problem are you trying to solve? The system will call the get() method if you're accessing the existing object, whether to look at it or modify it. It'll call the set() method if you're binding a new object to the attribute. DaveA ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
[Tutor] regexp: a bit lost
Hi, once again... I have a regexp that I am trying to use to make sure a line matches the format: [c*]n [c*]n n where c* is (optionally) 0 or more non-numeric characters and n is any numeric character. The spacing should not matter. These should pass: v1 v2 5 2 someword7 3 while these should not: word 2 3 1 2 Here is my test: s=re.search(r[\d+\s+\d+\s+\d], l) if s: #do stuff However: 1. this seems to pass with *any* string, even when l is a single character. This causes many problems and cannot happen since I have to ignore any strings not formatted as described above. So if I have for a in b: s=re.search(r[\d+\s+\d+\s+\d], l) if s: c.append(a) then c will have every string in b, even if the string being examined looks nothing like the pattern I am after. 2. How would I make my regexp able to match 0-n characters? I know to use \D*, but I am not sure about brackets or parentheses for putting the \D* into the parent expression (the \d\s one). 3. Once I get the above working, I will need a way of pulling the characters out of the string and sticking them somewhere. For example, if the string were v9 v10 15 I would want an array: n=[9, 10, 15] but the array would be created from a regexp. This has to be possible, but none of the manuals or tutorials on regexp say just how this is done. Mentions are made of groups, but nothing explicit (to me at least). -- Have a great day, Alex (msg sent from GMail website) mehg...@gmail.com; http://www.facebook.com/mehgcap ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] regexp: a bit lost
Alex Hall wrote: Hi, once again... I have a regexp that I am trying to use to make sure a line matches the format: [c*]n [c*]n n where c* is (optionally) 0 or more non-numeric characters and n is any numeric character. The spacing should not matter. These should pass: v1 v2 5 2 someword7 3 while these should not: word 2 3 1 2 Here is my test: s=re.search(r[\d+\s+\d+\s+\d], l) if s: #do stuff However: 1. this seems to pass with *any* string, even when l is a single character. This causes many problems and cannot happen since I have to [...] You want to match a whole line, so you should use re.match not re.search. See the docs: http://docs.python.org/library/re.html#matching-vs-searching You can also use re.split in this case: yes = v1 v2 5 2 someword7 3 .splitlines() yes = [line for line in yes if line.strip()] import re pattern = (\w*\d\s+?) # there may be a better pattern than this rx = re.compile(pattern) for line in yes: print [part for part in rx.split(line) if part] ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] regexp: a bit lost
On Fri, 1 Oct 2010 12:45:38 pm Alex Hall wrote:
Hi, once again...
I have a regexp that I am trying to use to make sure a line matches
the format: [c*]n [c*]n n
where c* is (optionally) 0 or more non-numeric characters and n is
any numeric character. The spacing should not matter. These should
pass: v1 v2 5
2 someword7 3
while these should not:
word 2 3
1 2
Here is my test:
s=re.search(r[\d+\s+\d+\s+\d], l)
Try this instead:
re.search(r'\d+\s+\D*\d+\s+\d', l)
This searches for:
one or more digits
at least one whitespace char (space, tab, etc)
zero or more non-digits
at least one digit
at least one whitespace
exactly one digit
However:
1. this seems to pass with *any* string, even when l is a single
character. This causes many problems
[...]
I'm sure it does.
You don't have to convince us that if the regular expression is broken,
the rest of your code has a problem. That's a given. It's enough to
know that the regex doesn't do what you need it to do.
3. Once I get the above working, I will need a way of pulling the
characters out of the string and sticking them somewhere. For
example, if the string were
v9 v10 15
I would want an array:
n=[9, 10, 15]
Modify the regex to be this:
r'(\d+)\s+\D*(\d+)\s+(\d)'
and then query the groups of the match object that is returned:
mo = re.search(r'(\d+)\s+\D*(\d+)\s+(\d)', 'spam42 eggs239')
mo.groups()
('42', '23', '9')
Don't forget that mo will be None if the regex doesn't match, and don't
forget that the items returned are strings.
--
Steven D'Aprano
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Re: [Tutor] regexp: a bit lost
with coffee: yes = v1 v2 5 2 someword7 3 .splitlines()[1:] no = word 2 3 1 2 .splitlines()[1:] import re pattern = (\w*\d\s+?)(\w*\d\s+?)(\d)$ rx = re.compile(pattern) for line in yes: m = rx.match(line) assert m print([part.rstrip() for part in m.groups()]) for line in no: m = rx.match(line) assert not m ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
