Re: [Tutor] newb help reading lines from csv
Dear Rob,
This caught me out as well for a long time.
As I understand it, csv.reader is a file-reader, which iterates ONCE
over the file. There may be more elegant solutions, but I do:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
inData = []
for row in reader:
inData.append[row]
ifile.close()
you can now loop through inData to your heart's desire.
HTH,
Matt
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[Tutor] newb help reading lines from csv
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
for row in reader:
print row
for row in reader:
print row
ifile.close()
This is a simplified version of what I am trying to do - loop through
a CSV file twice. Why does the second for loop not execute at all?
The first one prints the rows of the file just fine.
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Re: [Tutor] newb help reading lines from csv
Hi,
On Oct 22, 2012, at 12:20 PM, Dewhirst, Rob robdewhi...@gmail.com wrote:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
for row in reader:
print row
for row in reader:
print row
ifile.close()
This is a simplified version of what I am trying to do - loop through
a CSV file twice. Why does the second for loop not execute at all?
The first one prints the rows of the file just fine.
_
I believe csv module uses iterator so you need to run reader.seek(0) between
the for loops
Laszlo
http://twitter.com/LZAntal
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Re: [Tutor] newb help reading lines from csv
Dewhirst, Rob wrote:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
for row in reader:
print row
for row in reader:
print row
ifile.close()
This is a simplified version of what I am trying to do - loop through
a CSV file twice. Why does the second for loop not execute at all?
The first one prints the rows of the file just fine.
The first pass also exhausts the input feed -- you'll need to rewind or
reposition the next line pointer to the start of the file and I suspect
the easiest way is to reopen the file.
Emile
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Re: [Tutor] newb help reading lines from csv
On Mon, Oct 22, 2012 at 3:20 PM, Dewhirst, Rob robdewhi...@gmail.com wrote:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
for row in reader:
print row
for row in reader:
print row
ifile.close()
This is a simplified version of what I am trying to do - loop through
a CSV file twice. Why does the second for loop not execute at all?
The first one prints the rows of the file just fine.
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You need to close the file and re open to iterate again. You can't
reset the iterator back to the beginning without closing and
re-opening
--
Joel Goldstick
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Re: [Tutor] newb help reading lines from csv
Thanks Matt and Lazlo. I knew I must have been missing some counter
not being reset. Both of those options work fine.
You want to do ifile.seek(0) not reader.seek(0) at least from my testing.
On Mon, Oct 22, 2012 at 2:27 PM, Matt Williams m...@doctors.org.uk wrote:
Dear Rob,
This caught me out as well for a long time.
As I understand it, csv.reader is a file-reader, which iterates ONCE over
the file. There may be more elegant solutions, but I do:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
inData = []
for row in reader:
inData.append[row]
ifile.close()
you can now loop through inData to your heart's desire.
HTH,
Matt
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Re: [Tutor] newb help reading lines from csv
On Mon, Oct 22, 2012 at 3:28 PM, LZAntal lzan...@gmail.com wrote:
On Oct 22, 2012, at 12:20 PM, Dewhirst, Rob robdewhi...@gmail.com wrote:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
I believe csv module uses iterator so you need to run reader.seek(0) between
the for loops
You have to reset the file iterator with ifile.seek(0). You might also
want a new reader if you care about the line_num attribute, but
otherwise you can keep using the same reader.
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Re: [Tutor] newb help reading lines from csv
On Mon, Oct 22, 2012 at 3:35 PM, Dewhirst, Rob robdewhi...@gmail.com wrote:
Thanks Matt and Lazlo. I knew I must have been missing some counter
not being reset. Both of those options work fine.
You want to do ifile.seek(0) not reader.seek(0) at least from my testing.
On Mon, Oct 22, 2012 at 2:27 PM, Matt Williams m...@doctors.org.uk wrote:
Dear Rob,
This caught me out as well for a long time.
As I understand it, csv.reader is a file-reader, which iterates ONCE over
the file. There may be more elegant solutions, but I do:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
inData = []
for row in reader:
inData.append[row]
ifile.close()
you can now loop through inData to your heart's desire.
HTH,
Matt
If you want to learn more about python iterators this is a good place
to start: http://docs.python.org/howto/functional.html#iterators
or google python iterators. They are pretty cool to understand
--
Joel Goldstick
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Re: [Tutor] newb help reading lines from csv
On Mon, Oct 22, 2012 at 3:35 PM, Dewhirst, Rob robdewhi...@gmail.com wrote:
import csv
ifile = open('test.csv', r)
reader = csv.reader(ifile)
inData = []
for row in reader:
inData.append[row]
ifile.close()
you can now loop through inData to your heart's desire.
Alternatively:
import csv
with open('test.csv', 'rb') as ifile:
inData = list(csv.reader(ifile))
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Re: [Tutor] newb help reading lines from csv
Dewhirst, Rob wrote: Thanks Matt and Lazlo. I knew I must have been missing some counter not being reset. Both of those options work fine. You want to do ifile.seek(0) not reader.seek(0) at least from my testing. On Mon, Oct 22, 2012 at 2:27 PM, Matt Williams m...@doctors.org.uk wrote: [snip] Please do not top post. This list's etiquette is to write your response in-line or below the quoted text. Thank you. Ramit Prasad This email is confidential and subject to important disclaimers and conditions including on offers for the purchase or sale of securities, accuracy and completeness of information, viruses, confidentiality, legal privilege, and legal entity disclaimers, available at http://www.jpmorgan.com/pages/disclosures/email. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
bob gailer [EMAIL PROTECTED] wrote 3rd alternative: if c 'm': print c Wow! Amazingly I just assumed you couldn't directly compare characters with boolean tests. I don't know why I thought that since it must be possible for string comparisons, but I did. You learn something new every day, :-) Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
3rd alternative: if c 'm': print c after futzing around with interpreting the problem, I ended up with a solution that utilizes the character comparison. Write a program that prints the first letter of a string that comes after 'm' in the alphabet. s = this is my string for i in s: if i 'm': print i break Thanks for all the help everyone. Seems so obvious now.. ;-) I'm sure I'll be back with some more newb questions in the future. ;-) jeff. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
Should be replying to the listSorry :( On Thu, Apr 3, 2008 at 11:14 AM, Sander Sweers [EMAIL PROTECTED] wrote: On Thu, Apr 3, 2008 at 8:21 AM, Jeffrey Dates [EMAIL PROTECTED] wrote: 3rd alternative: if c 'm': print c snip Write a program that prints the first letter of a string that comes after 'm' in the alphabet. s = this is my string for i in s: if i 'm': print i break One potential problem you will have is with upper case letters. 'N' 'm' False To make input all lower case use .lower() 'N'.lower() 'm' True Greets Sander ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
Exellent suggestion! thanks! On Thu, Apr 3, 2008 at 2:17 PM, Sander Sweers [EMAIL PROTECTED] wrote: Should be replying to the listSorry :( On Thu, Apr 3, 2008 at 11:14 AM, Sander Sweers [EMAIL PROTECTED] wrote: On Thu, Apr 3, 2008 at 8:21 AM, Jeffrey Dates [EMAIL PROTECTED] wrote: 3rd alternative: if c 'm': print c snip Write a program that prints the first letter of a string that comes after 'm' in the alphabet. s = this is my string for i in s: if i 'm': print i break One potential problem you will have is with upper case letters. 'N' 'm' False To make input all lower case use .lower() 'N'.lower() 'm' True Greets Sander ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
[Tutor] Newb Learning Question
Greetings, I have no previous experience in scripting. Python is my first language... I'm currently trying to build a logic model for how to 'think' in Python, so please excuse my ignorance. Currently, I'm running through some basic 101 tutorials, to wrap my head around solving problems. I'm looking for some advice on how to solve the following exercise: Write a program that prints the first letter of a string that comes after 'm' in the alphabet. I hope this is not too elementary. I do understand basic, basic concepts. iteration, for loops, etc. Just having trouble with syntax, and how to format my logic. thank you in advance for any help or examples. Jeffrey Dates www.kungfukoi.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
Sorry forgot to post what I had so far: for code in range(ord(a), ord(z) +1): if code == ord(m): print chr(code +1) Now, this solves for the first letter after M, but doesn't do it via a string thanks, Jeffrey Dates www.kungfukoi.com On Wed, Apr 2, 2008 at 12:44 PM, Jeffrey Dates [EMAIL PROTECTED] wrote: Greetings, I have no previous experience in scripting. Python is my first language... I'm currently trying to build a logic model for how to 'think' in Python, so please excuse my ignorance. Currently, I'm running through some basic 101 tutorials, to wrap my head around solving problems. I'm looking for some advice on how to solve the following exercise: Write a program that prints the first letter of a string that comes after 'm' in the alphabet. I hope this is not too elementary. I do understand basic, basic concepts. iteration, for loops, etc. Just having trouble with syntax, and how to format my logic. thank you in advance for any help or examples. Jeffrey Dates www.kungfukoi.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
On Wed, Apr 2, 2008 at 12:50 PM, Jeffrey Dates [EMAIL PROTECTED] wrote: Sorry forgot to post what I had so far: for code in range(ord(a), ord(z) +1): if code == ord(m): print chr(code +1) Now, this solves for the first letter after M, but doesn't do it via a string thanks, Let's think about the problem in pseudocode: If the first letter in the string comes after m in the alphabet, print that letter. Otherwise, if the second letter comes after m in the alphabet, print *that* letter. etc. etc. So what you want is to *iterate* through the characters that make up the string (from start to end) until you find a character that comes after m. Your code above seems to *iterate* through all the characters from a to z, not the characters of a given string. See if you can fix that first, then we'll talk about the next step. Tony R. aka Taser Jeffrey Dates www.kungfukoi.com On Wed, Apr 2, 2008 at 12:44 PM, Jeffrey Dates [EMAIL PROTECTED] wrote: Greetings, I have no previous experience in scripting. Python is my first language... I'm currently trying to build a logic model for how to 'think' in Python, so please excuse my ignorance. Currently, I'm running through some basic 101 tutorials, to wrap my head around solving problems. I'm looking for some advice on how to solve the following exercise: Write a program that prints the first letter of a string that comes after 'm' in the alphabet. I hope this is not too elementary. I do understand basic, basic concepts. iteration, for loops, etc. Just having trouble with syntax, and how to format my logic. thank you in advance for any help or examples. Jeffrey Dates www.kungfukoi.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
Jeffrey Dates wrote: Greetings, I have no previous experience in scripting. Python is my first language... I'm currently trying to build a logic model for how to 'think' in Python, so please excuse my ignorance. Currently, I'm running through some basic 101 tutorials, to wrap my head around solving problems. I'm looking for some advice on how to solve the following exercise: Write a program that prints the first letter of a string that comes after 'm' in the alphabet. what I had so far: for code in range(ord(a), ord(z) +1): if code == ord(m): print chr(code +1) Now, this solves for the first letter after M which is NOT what the exercise wants! Consider are you ready?. Which character is the first that comes after 'm' in the alphabet.? BTW did you mean after m? Caps and lower case are different. , but doesn't do it via a string I for one am reluctant to just give an answer. I prefer to lead you to a solution. So, I suggest you write a program to: assign a candidate string to a variable (choose a string that has at least one letter that comes after 'm') test each character to see if it comes after 'm' print that character stop Do as much as you can, and ask more questions. -- Bob Gailer 919-636-4239 Chapel Hill, NC ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
That's Bob, and Tony, exactly what I'm looking for. ( not the answer, but the path to it... ) Let me get back to you with my result after I study this a bit. thanks!! Jeffrey Dates www.kungfukoi.com On undefined, bob gailer [EMAIL PROTECTED] wrote: Jeffrey Dates wrote: Greetings, I have no previous experience in scripting. Python is my first language... I'm currently trying to build a logic model for how to 'think' in Python, so please excuse my ignorance. Currently, I'm running through some basic 101 tutorials, to wrap my head around solving problems. I'm looking for some advice on how to solve the following exercise: Write a program that prints the first letter of a string that comes after 'm' in the alphabet. what I had so far: for code in range(ord(a), ord(z) +1): if code == ord(m): print chr(code +1) Now, this solves for the first letter after M which is NOT what the exercise wants! Consider are you ready?. Which character is the first that comes after 'm' in the alphabet.? BTW did you mean after m? Caps and lower case are different. , but doesn't do it via a string I for one am reluctant to just give an answer. I prefer to lead you to a solution. So, I suggest you write a program to: assign a candidate string to a variable (choose a string that has at least one letter that comes after 'm') test each character to see if it comes after 'm' print that character stop Do as much as you can, and ask more questions. -- Bob Gailer 919-636-4239 Chapel Hill, NC ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
Jeffrey Dates [EMAIL PROTECTED] wrote Let me get back to you with my result after I study this a bit. thanks!! One wee tip you might find useful. To test if a lertter comes after 'm you could a) create a string with all letters after m after_m = 'nopqrstuvwxyz' then test whether your characters were in after_m: if c in after_m: print c OR b) see if the ascii value of your character is bigger than the ascii value of 'm' And you can check the ascii value using ord() There are pros and cons to both approaches. Pick the one you like best, we can debate the ideal solution for any given case later... HTH, -- Alan Gauld Author of the Learn to Program web site http://www.freenetpages.co.uk/hp/alan.gauld ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb Learning Question
Alan Gauld wrote: Jeffrey Dates [EMAIL PROTECTED] wrote Let me get back to you with my result after I study this a bit. thanks!! One wee tip you might find useful. To test if a lertter comes after 'm you could a) create a string with all letters after m after_m = 'nopqrstuvwxyz' then test whether your characters were in after_m: if c in after_m: print c OR b) see if the ascii value of your character is bigger than the ascii value of 'm' And you can check the ascii value using ord() 3rd alternative: if c 'm': print c There are pros and cons to both approaches. Pick the one you like best, we can debate the ideal solution for any given case later... -- Bob Gailer 919-636-4239 Chapel Hill, NC ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] newb - Problem reading binary files
Elizabeth Finn wrote:
I need to read a file that is in binary format, and then convert some of
the values into integer values. These values can range from 1 to 4 bytes.
First question – is there an easy way to do this? I finally wrote my own
little utility to handle multi-byte integers because I couldn’t find a
built-in way (except for ord() which works only for single bytes)
Alan suggested the struct module. It doesn't directly support 3-byte
integers but perhaps you could pad them with a zero byte at the front.
struct does let you unpack a whole string at once.
The Construct library is a higher-level interface to similar
functionality. It doesn't seem to support 3-byte integers either but it
is extensible.
def getnum(num_str):
Given a string representing a binary number, return the number.
If string is more than one byte, calculate the number to return.
Assume that each byte is signed magnitude
x = len(num_str)
ans = 0
for i in range( x ):
nextstr = num_str[i:i+1]
ans = ans * 256
ans = ans + ord(nextstr)
return ans
Your loop could be written more simply as
for nextstr in num_str:
ans = ans * 256
ans = ans + ord(nextstr)
This “brute force” method usually works, but - now here is the other
question -sometimes the code does not pick up two full bytes when it is
supposed to. I open the file and read a block that I want into a string:
f=open(fname, 'rb')
f.seek(offset, 0)
block = f.read(2000)
Then for each number I pull the bytes from the string, then call
getnum() to calculate the number.
test = block[0:1] # 1 byte
test = block[1:4] # 3 bytes
test = block[4:6] # 2 bytes
test = block[20:12] # 2 bytes
test = block[1996:2000] #4 bytes
This method usually works, except that for some of the 2-byte numbers I
get only the first byte and first half of the second byte – for
instance: 'x06\x33’ comes out as ‘x063’. This is very confusing
especially because one 2-byte substring – “00 01” comes out as expected,
but “06 52” becomes “065”. Any ideas?
It seems to work for me. I wonder if you are confused about the input
you are giving it? Using your definition of getnum(), I get these results:
In [31]: getnum('\x06\x33')
Out[31]: 1587
In [33]: 6*256 + 0x33
Out[33]: 1587
In [34]: getnum('\x06\x52')
Out[34]: 1618
In [35]: 6*256 + 0x52
Out[35]: 1618
So it seems to be doing the right thing. Can you put
print repr(test)
print getnum(test)
into your test program and show us the results?
Kent
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[Tutor] newb - Problem reading binary files
This is probably a newbie question, and I apologize for the length but I have consulted several books / sites and havent found a good answer. I need to read a file that is in binary format, and then convert some of the values into integer values. These values can range from 1 to 4 bytes. First question is there an easy way to do this? I finally wrote my own little utility to handle multi-byte integers because I couldnt find a built-in way (except for ord() which works only for single bytes) def getnum(num_str): Given a string representing a binary number, return the number. If string is more than one byte, calculate the number to return. Assume that each byte is signed magnitude x = len(num_str) ans = 0 for i in range( x ): nextstr = num_str[i:i+1] ans = ans * 256 ans = ans + ord(nextstr) return ans This brute force method usually works, but - now here is the other question -sometimes the code does not pick up two full bytes when it is supposed to. I open the file and read a block that I want into a string: f=open(fname, 'rb') f.seek(offset, 0) block = f.read(2000) Then for each number I pull the bytes from the string, then call getnum() to calculate the number. test = block[0:1] # 1 byte test = block[1:4] # 3 bytes test = block[4:6] # 2 bytes test = block[20:12] # 2 bytes test = block[1996:2000] #4 bytes This method usually works, except that for some of the 2-byte numbers I get only the first byte and first half of the second byte for instance: 'x06\x33 comes out as x063. This is very confusing especially because one 2-byte substring 00 01 comes out as expected, but 06 52 becomes 065. Any ideas? - Finding fabulous fares is fun. Let Yahoo! FareChase search your favorite travel sites to find flight and hotel bargains.___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] newb - Problem reading binary files
Elizabeth Finn [EMAIL PROTECTED] wrote
binary format, and then convert some of the values into
integer values. These values can range from 1 to 4 bytes.
See the struct module, and for an exampole the binary file
sidebar in the file handling topic of my tutor. But caveat:
struct needs to know the sizes and types of data you are
reading in advance.
for some of the 2-byte numbers I get only the first byte
and first half of the second byte - for instance: 'x06\x33'
comes out as 'x063'. This is very confusing
Look closely and you will see that Python is telling you
that the 06 represents the hex value of the byte. The second
byte has no \x so is a character. The ASCII value of 0x33
is '3'...
hex(ord('3'))
'0x33'
...but 06 52 becomes 065. Any ideas?
Not on that one... x52 is 'R'... and chr(52) is '4'
--
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld
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Re: [Tutor] Newb ?
These both work (though neither is very graceful). text = hello message = for i in range(len(text)): message = message + text[(len(text)-i-1)] print message lst = list(text) newstr = for item in text: newstr += (lst.pop()) print newstr On 16/11/05, Chad Everett [EMAIL PROTECTED] wrote: Hello all, Have a problem here with a challenge from a book I am reading. Any help is much appreciated. I am trying to run a program that asks the user for a statement and then prints it out backwards. this is what I have. It does not print anything out. I assume that I have something out of whack with my high and low statements. Thanks for you help. print \n\nWelcome to the Backwards Message Display. print message = raw_input(\nPlease Enter a Message.) high = len(message) low = -len(message) print print message[high:low] print print raw_input(Please Press Enter to Exit) -- http://mail.python.org/mailman/listinfo/python-list ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb ?
How about - print \n\nWelcome to the Backwards Message Display. print message = raw_input(\nPlease Enter a Message.) msgAsList = [ char for char in message] msgAsList.reverse() reversedMessage = ''.join(msgAsList) I can't test that, but it should work. But, with regard to - print \n\nWelcome to the Backwards Message Display. print message = raw_input(\nPlease Enter a Message.) high = len(message) low = -len(message) print print message[high:low] print print raw_input(Please Press Enter to Exit) low will always be the first char of the string, won't it? In which case, It'd always be 0. or len(message) - len(message) ! -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ed Singleton Sent: Friday, 18 November 2005 6:11 a.m. To: tutor@python.org Subject: Re: [Tutor] Newb ? These both work (though neither is very graceful). text = hello message = for i in range(len(text)): message = message + text[(len(text)-i-1)] print message lst = list(text) newstr = for item in text: newstr += (lst.pop()) print newstr On 16/11/05, Chad Everett [EMAIL PROTECTED] wrote: Hello all, Have a problem here with a challenge from a book I am reading. Any help is much appreciated. I am trying to run a program that asks the user for a statement and then prints it out backwards. this is what I have. It does not print anything out. I assume that I have something out of whack with my high and low statements. Thanks for you help. print \n\nWelcome to the Backwards Message Display. print message = raw_input(\nPlease Enter a Message.) high = len(message) low = -len(message) print print message[high:low] print print raw_input(Please Press Enter to Exit) -- http://mail.python.org/mailman/listinfo/python-list ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor A new monthly electronic newsletter covering all aspects of MED's work is now available. Subscribers can choose to receive news from any or all of seven categories, free of charge: Growth and Innovation, Strategic Directions, Energy and Resources, Business News, ICT, Consumer Issues and Tourism. See http://news.business.govt.nz for more details. http://www.govt.nz - connecting you to New Zealand central local government services Any opinions expressed in this message are not necessarily those of the Ministry of Economic Development. This message and any files transmitted with it are confidential and solely for the use of the intended recipient. If you are not the intended recipient or the person responsible for delivery to the intended recipient, be advised that you have received this message in error and that any use is strictly prohibited. Please contact the sender and delete the message and any attachment from your computer. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb ?
Liam said: How about - print \n\nWelcome to the Backwards Message Display. print message = raw_input(\nPlease Enter a Message.) msgAsList = [ char for char in message] You could also do: msgAsList = list(message) list() takes any iterable and returns a list object. msgAsList.reverse() reversedMessage = ''.join(msgAsList) In Python 2.4, the following is also possible: reversedMessage = ''.join(reversed(list(message))) It's amazing how in Python even one-liners can be so pretty :-) Christian ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb ?
list() takes any iterable and returns a list object. Hmm, I did not know that the list(str) thing worked that way.That'll reduce the list comprehensions, but is it intuitive? Would a newbie see that and think that list(Hi) returns [Hi] or [H,i] ? reversedMessage = ''.join(reversed(list(message))) Yes, but for clarity when demonstrating a concept, one-liners should be minimised, I think. ;) But I agree, you can create some obscenely complicated one liners, which are still understandable. I find I have to force myself sometimes to refactor some of the ones I come up with, however. Good rule of thumb is when you're feeling impressed with your own cleverness, you probably need to refactor. (Thanks c2 wiki, for teaching me that.) -Original Message- From: Christian Wyglendowski [mailto:[EMAIL PROTECTED] Sent: Friday, 18 November 2005 9:31 a.m. To: Liam Clarke-Hutchinson; tutor@python.org Subject: RE: [Tutor] Newb ? Liam said: How about - print \n\nWelcome to the Backwards Message Display. print message = raw_input(\nPlease Enter a Message.) msgAsList = [ char for char in message] You could also do: msgAsList = list(message) list() takes any iterable and returns a list object. msgAsList.reverse() reversedMessage = ''.join(msgAsList) In Python 2.4, the following is also possible: reversedMessage = ''.join(reversed(list(message))) It's amazing how in Python even one-liners can be so pretty :-) Christian A new monthly electronic newsletter covering all aspects of MED's work is now available. Subscribers can choose to receive news from any or all of seven categories, free of charge: Growth and Innovation, Strategic Directions, Energy and Resources, Business News, ICT, Consumer Issues and Tourism. See http://news.business.govt.nz for more details. http://www.govt.nz - connecting you to New Zealand central local government services Any opinions expressed in this message are not necessarily those of the Ministry of Economic Development. This message and any files transmitted with it are confidential and solely for the use of the intended recipient. If you are not the intended recipient or the person responsible for delivery to the intended recipient, be advised that you have received this message in error and that any use is strictly prohibited. Please contact the sender and delete the message and any attachment from your computer. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Newb ?
Orri said: Or you could just do the following: print \n\nWelcome to the Backwards Message Display. print message = raw_input(\nPlease Enter a Message.) print message[::-1] Interesting. I forgot about the 'step' option when slicing. This is the equivalent of print ''.join(reversed(message)), since reversed works on any iterable sequence, including strings. Ha! Good call. Makes it even clearer. In any case, the syntax for this sort of thing in general is: sequence[start:stop:step], with start defaulting to 0, step defaulting to sys.maxint (which, for all intents and purposes, means the end of the string), and step defaulting to 1. However, when step is negative, start and end switch defaults. So by doing [::-1], you're telling Python to return the values of the sequence that can be found from the end to the start Cool. Thanks for this explanation. Christian ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] newb problem running the translator (fwd)
On Apr 9, 2005, at 10:36, Danny Yoo wrote: -- Forwarded message -- Date: Fri, 8 Apr 2005 22:03:58 EDT From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: newb problem running the translator I will try to make this quick. I am a newb to python, and programming at that, but i am realy interested. I have been looking at simple programs to be run through the shell but i cannot figure out the translator. When i save program i have tried to tell it to opoen it in the translator. I have been looking through several websites and looked through the documents my python installation came with. On one computer i am running Windows Xp and on another win98SE. If you could explain to me how to open a program through the translator i would appreciate it alot. What exactly do you call the translator? If you mean the compiler, it's normal that you can't find it: there is none. Python is an interpreted language (well, bytecode, but let's not get into that, shall we?). To run your Python programs, you call the Python interpreter on them: python foo.py, for example, runs the foo.py program. -- Max maxnoel_fr at yahoo dot fr -- ICQ #85274019 Look at you hacker... A pathetic creature of meat and bone, panting and sweating as you run through my corridors... How can you challenge a perfect, immortal machine? ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
