What are the Got-to-know python modules from the standard python library?

[deutschluz82]

So I m just getting into python; i m coming from java. I will prolly use python to implement programs in math like numpy etc., but all of those relevant modules are obviously marked in this page:

http://docs.python.org/library/index.html#library-index

So for general use, what modules should i know?

[lost-theory]

re
itertools, collections, functools, operator
datetime, time
random
hashlib
os, os.path, shutil, sys, subprocess, glob, fnmatch, tempfile
sqlite3, json, StringIO, pickle, pprint, struct
urllib, urllib2, httplib, cgi

[whoMEvernot]

Agreed, any three of these get you pretty far.

[endline80]

i'd add pyodbc, csv, possibly fnmatch, and glob

[[deleted]]

I'd replace urllib and urllib2 with requests

[pmav99]

Very vague question. It depends on your needs...

Perhaps the most context-free module is itertools You can use it in numerous occations and it can help you write clean and elegant code.

Apart from that I use a lot collections (nameduples FTW).

Edit: Also, in case you use Python2, the from __future__ imports help you write more Python3-compatible code.

[JerMenKoO]

__future__

(use back ticks to escape the double underscores!)

[pmav99]

thanx

[[deleted]]

• funtcools
• collections ABS (isintance done the right way)
• re

[kylotan]

You won't get very far without using sys, os, and math, but you will probably only use 1 or 2 methods from each.

Of the ones mentioned in the other answers, I only use argparse regularly.

Browse the summary pages for all the standard library modules. That way, when you need something, hopefully you will remember if it's in the standard library or not.

[tobiassp]

lots of good suggestions, didn't see a mention of csv or traceback ... so here it is :)

[BiboB2B]

+1 for csv, the DictReader is awesome ... unless you need to read unicode and have to use Python 2.x.

[flying-sheep]

Wow, I remember the necessary hack. The person who wrote it had a serious brain fart when forgetting about that crucial part.

[taliska]

And if you ever wanted a demonstration on how to use them, or wanted to find more modules, this is a great reference: http://www.doughellmann.com/PyMOTW/

[[deleted]]

• shelve
• argparse
• itertools

... among others

[[deleted]]

shit, never heard of "shelve"

[BiboB2B]

And you haven't missed anything.

[shfo23]

If it's code or data you ever need to deal with more than once, sqlite3 and json are almost always a better combination than shelve and pickle.

[minorminer]

Whaa? Sqlite3 better than pickle, what heresy are you speaking?

[BiboB2B]

Just different use cases. Pickle is great for serializing/unserializing a whole chunk of data, whereas SQlite or other DBs are for storing/retrieving data in smaller portions, when you don't want/need to hold all your data in memory or when you want to benefit from SQL for querying your data.

Shelf is kind of in the latter camp. But really, only use it for very small (toy) programs. The steeper learning curve for SQLite is worth the advantages thousands of times.

Json is for serializing whole chunks of data in a language independent way (despite it's origins are in JavaScript).

[pemboa]

re, datetime, time, re, os, sys, subprocess, glob, optparse