Tips and Tricks

5/1/2014

Matthew Cahn

mcahn@princeton.edu

Goals

1. Getting the job done
2. Maintainability
3. Style

Using if __name__ == '__main__' so your module can be imported.

Documenting with doc strings so help() works.

Command line parsing with optparse (if you're using an older version of Python) (Python < 2.7).

pyversion.py

Command line parsing.

commandline1.py -- Using sys.argv directly -- BAD
commandline2.py -- argparse (Python 2.7 or newer) -- define your options with code
commandline3.py -- docopt (add-on module) -- define your options with documentation

Interleave two or more lists.

zip.py

Produce a counter while iterating.

enumerate.py

The built-in set type -- unions, intersections, etc.

sets.py -- (Python >= 2.6)

List, dictionary, and set comprehensions -- a concise way to create these objects.

comprehensions.py  -- (Python >= 3.0.0 for list, dictionary and set comprehensions)
                      (Python >= 2.0.0 -- list comprehensions only)

The dictionary setdefault method -- set the default value for a key, or return the current value.

The doctest module -- test a module according to the doc string.

Everything in Python is a reference.

dictsAndDoctest.py

The collections module -- Counter, defaultdict

collectionsDemo.py -- (Counter: Python >= 2.7, defaultdict: Python >= 2.5)

Function argument passing -- positional, keyword, and variable number of arguments.

arguments.py -- (Any Python version, but >= 3.0.0 for this particular example)

The logging module -- send messages to the screen, files, email, etc.

loggingDemo.py
loggingDemo.conf

Documentation:

The Global Module index: docs.python.org

docopt.org -- For the docopt module.

Also useful:

The Python Cookbook: http://code.activestate.com/recipes/langs/python/