Python information and short questions megathread.

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Spelter: Jul 18, 2007; Are you puissant?

Cicero posted:

I'm using the subprocess module to execute shell commands inside a python script. I want the stdout from these new processes to basically shut up because they're really verbose but the print statements inside my python script to continue working. Right now it seems to be either both or none. I'm working on windows if that matters.

Probably best to just redirect stderr and stdout of the command you're running to NUL, like this:

code:

with open(os.devnull, 'w') as f_null:
    returncode = subprocess.call("somecommand", stdout = f_null, stderr = subprocess.STDOUT)

Since it uses os.devnull it should work on Windows and UNIX. This won't affect the output of your script, just the subprocess.

# ? Aug 6, 2011 00:31

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# ? Jun 11, 2024 20:03

JetsGuy: Sep 17, 2003; science + hockey
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Cicero posted:

I'm using the subprocess module to execute shell commands inside a python script. I want the stdout from these new processes to basically shut up because they're really verbose but the print statements inside my python script to continue working. Right now it seems to be either both or none. I'm working on windows if that matters.

I had a similar issue with a batch processing routine, and ended up doing this:

code:

from subprocess import call

(create sh_script1.sh)

log_proc1=open("sh_script1.log","w")
call(["sh","sh_script1.sh"],stdout=sh_proc1)

I liked this approach because it gave me the benefit of having the output from the routines I was running somewhere in a log file. It became very useful for tracking down errors that prop up when processing a data set that doesn't behave as expected.

EDIT: oh damnit, missed that there was a new page. I like my method a litle better, but it depends on how useful the output would be for you.

# ? Aug 6, 2011 05:08

Lurchington: Jan 2, 2003; Forums Dragoon

Cicero posted:

I'm using the subprocess module to execute shell commands inside a python script. I want the stdout from these new processes to basically shut up because they're really verbose but the print statements inside my python script to continue working. Right now it seems to be either both or none. I'm working on windows if that matters.

I've never actually had subprocess commands outputting anything unless I specifically tell it to. Setting the stderr and stdout kwargs to subprocess.PIPE gives you a file-like object that has the output streams with no issues.

Here's the PMOTW on subprocess, and it's pretty simple: http://blog.doughellmann.com/2007/07/pymotw-subprocess.html

On the other handle if you're just blindly calling subprocess.call everywhere, then yeah you'd get the command output interfering with your print statements

# ? Aug 6, 2011 05:16

tef: May 30, 2004; -> some l-system crap ->

In subprocess, the child inherits stdout from the parent by default.

Try passing stdout=subprocess.PIPE into the subprocess command

http://docs.python.org/library/subprocess.html

When you do this, the popen object returned will have a stdout attribute you can read from and close, like a file handle.

# ? Aug 6, 2011 12:01

duck monster: Dec 15, 2004

tef posted:

By the way, it is a bag of functions and variables as implemented within python. Python is not message style OO like Smalltalk, Obj-C or Ruby, it is closer to Simula style OO.

If you want to write in smalltalk so much, just write in smalltalk :-)

Its a bag of functions and variables in smalltalk too, if you really think about it. The diffrence amounts to syntactical sugar, really.

It doesn't matter. I'm talking about how to think in OO, and modelling the problem is pretty much your canonical approach.

# ? Aug 7, 2011 07:42

Doctor Claw: Dec 25, 2007; I'll get you next time Gadget - next time!

As the OP hasn't been updated in nearly a year and a half, what is the best online resource for learning Python? I know HTML, CSS, PHP, Visual Basic (heh) and C++, I'm looking to learn Python for fun.

# ? Aug 7, 2011 16:38

spankweasel: Jan 4, 2006

Doctor Claw posted:

As the OP hasn't been updated in nearly a year and a half, what is the best online resource for learning Python? I know HTML, CSS, PHP, Visual Basic (heh) and C++, I'm looking to learn Python for fun.

I constantly point folks who have a programming background at the MIT course in the OP. It's very well done and doesn't really go into the tedium of: "This is an if-statement ... This is a for-loop ..." because (I assume) MIT assumes that people know the ultra basics of programming, even in the intro level.

# ? Aug 7, 2011 19:04

Yoshimo: Oct 5, 2003; Fleet of foot, and all that!

spankweasel posted:

I constantly point folks who have a programming background at the MIT course in the OP. It's very well done and doesn't really go into the tedium of: "This is an if-statement ... This is a for-loop ..." because (I assume) MIT assumes that people know the ultra basics of programming, even in the intro level.

What would be the best guide for people who DID want all that if-statement/for-loop information?

# ? Aug 7, 2011 19:07

TasteMyHouse: Dec 21, 2006

Yoshimo posted:

What would be the best guide for people who DID want all that if-statement/for-loop information?

http://learnpythonthehardway.org/

# ? Aug 7, 2011 19:30

spankweasel: Jan 4, 2006

TasteMyHouse posted:

http://learnpythonthehardway.org/

this. a thousand times this.

# ? Aug 8, 2011 01:11

JetsGuy: Sep 17, 2003; science + hockey
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TasteMyHouse posted:

http://learnpythonthehardway.org/

Seconding this. I didn't learn python this way the first time, but when I went through this, I learned so much more about Python than I ever did by just going seat of the pants of "how the hell do I do this"??

# ? Aug 9, 2011 04:44

Harold Ramis Drugs: Dec 6, 2010; by Y Kant Ozma Post

I stuck on the last part of a major project for my Python programming class. The program we're writing has to do all of the following things:

1.) Use a card object defined by the teacher to determine the value of a 5 card poker hand containing 5 cards.

2.) Take a numeric (positive integer) input from the user and repeat step 1 as many times. Record all of the hands to a text file

3.) Perform a simple statistical analysis of all of the hands collected from steps 1 and 2, and record this to a text file as well.

4.) If the user enters an input on step 2 that's not a positive integer, prompt the user to re-enter the input.

I can't for the life of me figure out part 4. Right now, the first part of my code looks like this:

code:

def main():
    
    xlimit = int(input('How many poker hands would you like to analyze? '))
    sfcount = 0
    fkcount = 0
    fhcount = 0
    fcount = 0
    scount = 0
    tkcount = 0
    tpcount = 0
    pcount = 0
    hccount = 0
    for a in range (xlimit):
        hand =[]
        for x in range(5):
            c = Card()
            for card in hand:
                while c.rank == card.rank and c.suit == card.suit:
                    c = Card()
            hand.append(c)
            hand.sort(key=lambda Card: Card.rank)

Is there a way I could put an 'if' or a 'while' statement on the first couple lines of code that will recursively restart the main function if the first input is not a positive integer?

Note: this is just the first couple lines of code, I don't see the need to post the entire thing.

# ? Aug 9, 2011 05:17

TOO SCSI FOR MY CAT: Oct 12, 2008; this is what happens when you take UI design away from engineers and give it to a bunch of hipster art student "designers"

Harold Ramis Drugs posted:

Is there a way I could put an 'if' or a 'while' statement on the first couple lines of code that will recursively restart the main function if the first input is not a positive integer?

Yep!

(before you ask "how?", you do it just like you said to do it)

You could also put the input into its own procedure, which returns when the user has entered a positive integer.

# ? Aug 9, 2011 05:20

duck monster: Dec 15, 2004

What are peoples recomendations on editors. I cant keep pycharm stable on Lion anymore with its constant lockups, and for the loving life of me I cant get eclipse to recognise its python path source directories for django. I'm losing days of work to this poo poo and its driving me loving insane.

e: Oh great aptana is just an eclipse rebrand with that crazy retarded virtual file-structure poo poo. Just give me a directory listing you over-engineering java wingnuts grrrrrrrrr

e2: Ok, 15 minutes of "rebuilding workspace" later, I think Aptana just failed the audition. :/ Any other recomendations for a non eclipse or IDEA based python editor that "gets" django?

e3: BBedit cant have different docs in a split window. Delete. :suicide:

What else is there?

e4: Oh hey jEdit is ugly as gently caress, but is stable , highlights python and html/js properly, has a multi-doc split windows and appears to just work. You'll do , you ugly little text editor! Shame about the eye-searing font though :/

e5: Oh hey sublime-text is pretty drat sweet!

duck monster fucked around with this message at 08:27 on Aug 9, 2011

# ? Aug 9, 2011 05:26

Harold Ramis Drugs: Dec 6, 2010; by Y Kant Ozma Post

Janin posted:

Yep!

(before you ask "how?", you do it just like you said to do it)

You could also put the input into its own procedure, which returns when the user has entered a positive integer.

I'm feeling pretty retarded now, and I've been trying different types of 'while' and 'if' loops to get this working. Could you please show me how to make an input statement that will recursively restart the main function if any non-integer or integer < 1 is entered? I'm kicking myself in the head right now.

VVVVV Thanks VVVVVV

Harold Ramis Drugs fucked around with this message at 06:53 on Aug 9, 2011

# ? Aug 9, 2011 06:30

TOO SCSI FOR MY CAT: Oct 12, 2008; this is what happens when you take UI design away from engineers and give it to a bunch of hipster art student "designers"

Harold Ramis Drugs posted:

I'm feeling pretty retarded now, and I've been trying different types of 'while' and 'if' loops to get this working. Could you please show me how to make an input statement that will recursively restart the main function if any non-integer or integer < 1 is entered? I'm kicking myself in the head right now.

Recursive main, checking for negative integers:

code:

def main():
  xlimit = int(input('How many poker hands would you like to analyze? '))
  if xlimit < 1:
    return main()

Separate function, with while loop:

code:

def input_positive_integer():
  while True:
    xlimit = int(input('How many poker hands would you like to analyze? '))
    if xlimit >= 1:
      return xlimit

def main():
  xlimit = input_positive_integer()

Separate function, also handling non-numeric inputs:

code:

def input_positive_integer():
  while True:
    raw = raw_input('How many poker hands would you like to analyze? ')
    try:
      xlimit = int(raw)
      if xlimit >= 1:
        return xlimit
    except ValueError:
      pass

# ? Aug 9, 2011 06:46

Lurchington: Jan 2, 2003; Forums Dragoon

duck monster posted:

What are peoples recomendations on editors. I cant keep pycharm stable on Lion anymore with its constant lockups, and for the loving life of me I cant get eclipse to recognise its python path source directories for django. I'm losing days of work to this poo poo and its driving me loving insane.

e: Oh great aptana is just an eclipse rebrand with that crazy retarded virtual file-structure poo poo. Just give me a directory listing you over-engineering java wingnuts grrrrrrrrr

e2: Ok, 15 minutes of "rebuilding workspace" later, I think Aptana just failed the audition. :/ Any other recomendations for a non eclipse or IDEA based python editor that "gets" django?

e3: BBedit cant have different docs in a split window. Delete. What else is there?

e4: Oh hey jEdit is ugly as gently caress, but is stable , highlights python and html/js properly, has a multi-doc split windows and appears to just work. You'll do , you ugly little text editor! Shame about the eye-searing font though :/

e5: Oh hey sublime-text is pretty drat sweet!

It's pretty barebones, but I like TextWrangler when doing one-off scripting.

I run PyCharm 1.5.3 on Lion (new mac mini) with no issues at all so I'm confused what's happening to you.

VVV PyScripter is alright in general, and since duck monster is on Mac, I'll mention that I was able to get it *working* with Wine on mac

Lurchington fucked around with this message at 21:11 on Aug 9, 2011

# ? Aug 9, 2011 14:23

_aaron: Jul 24, 2007; The underscore is silent.

duck monster posted:

What are peoples recomendations on editors.

I've had pretty decent luck with PyScripter. I haven't done much complicated work though, and I don't use any "advanced" features, so YMMV.

edit: ^^ Totally missed that he wanted something Mac-specific. Oh well; I'll leave it here for others who want a nice, free, Windows-only (or Wine, apparently) editor.

_aaron fucked around with this message at 01:11 on Aug 10, 2011

# ? Aug 9, 2011 17:05

TasteMyHouse: Dec 21, 2006

MacVim

# ? Aug 9, 2011 17:11

Grabulon: Jul 25, 2003

People all over the internet recommend Dive into Python, but it's not popular around here, right?

# ? Aug 9, 2011 18:01

Thermopyle: Jul 1, 2003; ...the stupid are cocksure while the intelligent are full of doubt. �Bertrand Russell

Grabulon posted:

People all over the internet recommend Dive into Python, but it's not popular around here, right?

It's terrible.

# ? Aug 9, 2011 18:25

madkapitolist: Feb 5, 2006

Hi guys I am very new to python and I am trying to write a script that pulls the newest file (this server gets a data dump every hour) from a sftp sever. I played around with the paramiko module and was able to write a script to pull a file of a certain name but I am completely lost when it comes to determining the newest file. Im not sure where to start, and I supposed to interpret os.stat? The files do have naming scheme which incorporates time/date etc etc. Any tutorials out there? Thanks

# ? Aug 9, 2011 19:00

Janitor Prime: Jan 22, 2004; PC LOAD LETTER

What da fuck does that mean; Fun Shoe

I recommend you use Fabric instead of paramiko, it has a nicer API built on top of paramiko. I've been using it to remote deploy our server stuff and it's really nice.

# ? Aug 9, 2011 19:10

Lurchington: Jan 2, 2003; Forums Dragoon

I'd recommend paramiko when all you need is to log in and execute a remote script and maybe get the output. Otherwise I agree that Fabric is better for the heavier stuff. For what it's worth, it sounds like rsync with ssh keys is basically what you want?

# ? Aug 9, 2011 21:12

DICTATOR OF FUNK: Nov 6, 2007; aaaaaw yeeeeeah

duck monster posted:

What are peoples recomendations on editors. I cant keep pycharm stable on Lion anymore with its constant lockups, and for the loving life of me I cant get eclipse to recognise its python path source directories for django. I'm losing days of work to this poo poo and its driving me loving insane.

e: Oh great aptana is just an eclipse rebrand with that crazy retarded virtual file-structure poo poo. Just give me a directory listing you over-engineering java wingnuts grrrrrrrrr

e2: Ok, 15 minutes of "rebuilding workspace" later, I think Aptana just failed the audition. :/ Any other recomendations for a non eclipse or IDEA based python editor that "gets" django?

e3: BBedit cant have different docs in a split window. Delete. What else is there?

e4: Oh hey jEdit is ugly as gently caress, but is stable , highlights python and html/js properly, has a multi-doc split windows and appears to just work. You'll do , you ugly little text editor! Shame about the eye-searing font though :/

e5: Oh hey sublime-text is pretty drat sweet!

Coda is pretty great. Maybe TextMate?

They're both worth the price. TextMate is more flexible plugin-wise but Coda's integrated SFTP is way better than the available TextMate plugins.

# ? Aug 9, 2011 22:14

duck monster: Dec 15, 2004

I'm pretty happy with Sublime text 2 at the moment. It seems to hit my feature list loving nicely and it appears to "get" django pretty well.

# ? Aug 10, 2011 06:38

mdxi: Mar 13, 2006; to JERK OFF is to be close to GOD... only with SPURTING

I just started my first project of decent scale in Python. This, of course, means testing. Except that I really didn't like the look of unittest, and nose, and py.test (AKA JUnit). So I ported a teensy testing lib that I wrote for Javascript, and added a runner/harness script. If you're familiar with Perl's Test::More, it'll look familiar.

https://github.com/firepear/nanotest-py/

Let me know if it's of use to you, and/or if you have concrete requests for improvement.

# ? Aug 10, 2011 06:56

Profane Obituary!: May 19, 2009; This Motherfucker is Dead

duck monster posted:

I'm pretty happy with Sublime text 2 at the moment. It seems to hit my feature list loving nicely and it appears to "get" django pretty well.

I'm trying out ST2 also, At the moment I like it over pycharm somewhat, I still have some problems with it over pycharm, like it's horrible spell checker, the fact that it doesn't seem to be able to handle virtualenvs/tab completion (least I havn't found out how yet), not saving your open files when switching projects, and no tab complete inside of strings for django settings.

# ? Aug 10, 2011 09:45

tripwire: Nov 19, 2004; _{ghost flow}

Thermopyle posted:

It's terrible.

Really? I just compared it and it is a lot more sensible and readable than Zed Shaw's self congratulatory wank fest.

# ? Aug 10, 2011 14:47

devilmouse: Mar 26, 2004; It's just like real life.

duck monster posted:

I'm pretty happy with Sublime text 2 at the moment. It seems to hit my feature list loving nicely and it appears to "get" django pretty well.

It's also written in python, if you want to extend it. The API is pretty nice too. If I used a GUI, it'd be Sublime 2!

# ? Aug 10, 2011 18:41

JetsGuy: Sep 17, 2003; science + hockey
=
LASER SKATES

I've used IDLE and had no real issues with it. I know it's not liked very much in Python editor circles though.

Aquamacs might be a good alternative, and really Aquamacs is awesome as it is.

# ? Aug 11, 2011 05:15

Angryhead: Apr 4, 2009; Don't call my name
Don't call my name
Alejandro

Hello everyone, quite new to Python/programming in general and I'm trying to remove certain characters from a string.

code:

allLines = allLines.replace('+', ' ')
allLines = allLines.replace('.', ' ')
allLines = allLines.replace('>', ' ')
and so on

This gets the job done, but I'm guessing that there's some kind of way to do it more efficiently.
Using Python 3.2 in case that matters.

# ? Aug 11, 2011 10:30

Red Mike: Jul 11, 2011

code:

chars = '+.>'
for char in chars:
    line.replace(char,' ')

This is a somewhat readable solution. You could even use some sort of one-liner that involves map(), I believe. Not that it'd help readability.

# ? Aug 11, 2011 10:54

tef: May 30, 2004; -> some l-system crap ->

Angryhead posted:

Hello everyone, quite new to Python/programming in general and I'm trying to remove certain characters from a string.

This gets the job done, but I'm guessing that there's some kind of way to do it more efficiently.
Using Python 3.2 in case that matters.

Regex (aka regular expressions) are a powerful way to process text.

http://docs.python.org/py3k/library/re.html#re.sub

# ? Aug 11, 2011 12:10

YO MAMA HEAD: Sep 11, 2007

I resisted learning regexes (regeces?) for a long time (I'm a total hobbyist) until I did some screen scraping and really needed them. I like Red Mike's solution to this problem (and it's probably a handy reminder that you can iterate through strings so easily) but don't wait as long as I did to dive into regex!

# ? Aug 11, 2011 20:24

Graviton v2: Mar 2, 2007; by angerbeet

3rd'd, the syntax is a bit rough (english slang meaning difficult) but skys the limit once you get over that hump.

# ? Aug 11, 2011 20:33

Thermopyle: Jul 1, 2003; ...the stupid are cocksure while the intelligent are full of doubt. �Bertrand Russell

tripwire posted:

Really? I just compared it and it is a lot more sensible and readable than Zed Shaw's self congratulatory wank fest.

Not that I keep up with beginner python books (for example, I don't know who the hell Zed Shaw is or what book you're talking about), but when I was first learning python and programming (neglecting the fact that I learned QBasic 20 years ago) a couple years ago, Dive into Python was very irritating.

I'm not alone in my feeling that it's not very good:

quote:

Dive Into Python isn't just bad because of the use of ODBC, it's also just full of bad initial examples. Take a look at your first Python program and boggle at all the bizarre stuff a beginner has to suddenly comprehend:

A function, with a giant doc comment right away.
Weird underscore variables with a bad font making it look like one underscore.
A list comprehension for-loop to join a string using a format string off a tuple.
A dict, formatted with backslash chars that aren't even needed.
Holy crap, how in the hell is that a good first example? Even worse is it starts a trend within the book of using ODBC as a theme to teach Python.

I get that everyone learns in different ways, but it certainly seems to me that most people won't find Dive into Python a very good beginners book.

FWIW, I struggled with Dive Into Python for awhile before switching to Python for Software Design - How to Think Like a Computer Scientist and breezing through it and learning a ton.

# ? Aug 11, 2011 21:35

Graviton v2: Mar 2, 2007; by angerbeet

I found the offical documentation a bit poo poo to be honest. Got lots more out of the community in general. Go fire up that browser!

# ? Aug 11, 2011 21:42

Yay: Aug 4, 2007

Thermopyle posted:

I'm not alone in my feeling that it's not very good

Even if you don't know who he is, you know you're citing Zed Shaw there, in a discussion of whether (Zed Shaw's) LPTHW is a self-congratulatory wank fest, or a better source than Dive into Python?

I too, think the actual python docs are pretty dreadful. At least they've improved; <=2.5 docs were a nightmare both to navigate and read - the new sphinx docs are a godsend, in that respect.

# ? Aug 11, 2011 22:10

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# ? Jun 11, 2024 20:03

Kimasu v2.0: Jan 19, 2001; Forum Veteran

Since we're talking about LPTHW, I started reading just for fun. I've been doing the "extra credit", but I am stuck on Example 17:

code:

from sys import argv
from os.path import exists

script, from_file, to_file = argv

input = open(from_file)
indata = input.read()

output = open(to_file, 'w')
output.write(indata)

output.close()
input.close()

Copy from one file to another. In the extra credit he says that he could do the whole program with one line of code. Well, I got the main part narrowed down to one line, but then I cannot figure out how to close the files.

code:

from sys import argv
from os.path import exists

script, from_file, to_file = argv

open(to_file, 'w').write(open(from_file).read())

All of the documentation I can find on close() seems to need a variable assigned to it, as I tried to_file.close() but that didn't work. What am I missing? My code runs and works just fine, but I'm assuming it is leaving the file open, correct?

# ? Aug 11, 2011 22:21

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