Good tricks

itertools is your friend

The itertools module is a bit of Python arcana that many people overlook.  For an in-depth look , Doug Hellman's PyMOTW article is a great overview.. Here are some of the highlights:

itertools.chain   is a fast way to string a list of iterables together. For example, you might have a list of lists - say, a bunch of component selections in Maya - and want to combine them into a single list.  It creates a generator that you can run through one item at a time or convert to a list with a list comprehension

import itertools
cube_verts =  ['pCube1.vtx[1]', 'pCube1.vtx[2]', 'pCube1.vtx[4]', 'pCube1.vtx[5]']
sphere_verts = ['pSphere1.vtx[10]', 'pSphere1.vtx[11]', 'pSphere1.vtx[12]', 'pSphere1.vtx[99]']
plane_verts = ['pPlane1.vtx[2]', 'pPlane1.vtx[20]', 'pPlane1.vtx[200]', 'pPlane1.vtx[202]']

for item in itertools.chain(cube_verts, sphere_verts, plane_verts):
    print item

#pCube1.vtx[1]
#pCube1.vtx[2]
#pCube1.vtx[4]
#pCube1.vtx[5]
#pSphere1.vtx[10]
#pSphere1.vtx[11]
#pSphere1.vtx[12]
#pSphere1.vtx[99]
#pPlane1.vtx[2]
#pPlane1.vtx[20]
#pPlane1.vtx[200]
#pPlane1.vtx[202]

itertools.product   will give you a generator that produces all the combinations of multiple iterable items. For example:

axes = ('x', 'y', 'z')
dimensions = (-1, 0, 1)
print [i for i in itertools.product(axes, dimensions)]
# [('x', -1), ('x', 0), ('x', 1), ('y', -1), ('y', 0), ('y', 1), ('z', -1), ('z', 0), ('z', 1)]

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Coding Tips

Maya list returns

Before maya 2014, cmds had several commands with an annoying, anti-pythonic behaviour: if you ask a question that usually returns a list but get no results, Maya will return None instead of an empty list. The most common example is a call to cmds.ls which returns nothing:

good_stuff = cmds.ls(type='mesh')
for item in good_stuff:
    do_something(item)
# ERROR: NoneType is not iterable

Luckily, Python has a handy language feature that makes it easy to avoid this trap without an extra if test. If you change the ls like so:

good_stuff = cmds.ls(type='mesh') or []
for item in good_stuff:
    do_something(item)

The 'or []' will pass a list result with something in it unchanged; but if the result is None, the or will substitute the empty list. Everything downstream from there can rely on the presence of a real list, even if it's empty

Maya like selection-or-list behavior

If you want to make a function that behaves like the default maya commands -- that is, it works on arguments you pass or on selected objects -- you can combine the *args variable input and the or [] trick to make a nice one liner :
 
    def mayalike(*args):
         my_objects = args or cmds.ls(sl=True) or []
         for item in my_objects:
               #do stuff

This will use args if provided, ls-sl if not, and [] if there is nothing selected

multiple assignment

python has a handy trick of unpacking iterables in a single assigment call.  This lets you write things like:

rotation = [ 0, 90, 0 ]

rx, ry, rz = rotation

 which saves some annoying boilderplate.  It can be especially useful when dealing with functions that produce tuple or list results:

filename, extension = os.splitext(completefilename)

which is much more elegant than

results = os.splitext(completefilename)

filename = results[0]

extension = results[1]

It's a good idea, though, to resist the temptation to overdo it: if you find yourself unpacking long tuples a lot:

name, address, state, zip, phone = customer

that's a good sign that customer should be a dictionary, a class, or a namedtuple so you can parse it reliably:

Learn to love Mayapy

If' your doing a lot of work that involves restarting and reloading maya - particularly if you're iterating on one script that involves a bunch of setup work -- the common trick is to keep all of your steps in a python tab in your listener.  It's better than nothing, but it's still pretty slow.

If what you're working on does not require GUI access, you can use MayaPy.exe and the -c and -i flags to get into your script quickly. The -c flag launches mayapy and runs a command, and the -i flag keeps the  interpreter running. So you can boot mayapy directly into a running, headless copy of maya python like this:

path/to/maya.py.exe -i -c "import maya.standalone; maya.standalone.initialize()"

and obviously you could put your test setup in a separate module and import that after standalone. I've found this saves me a huge amount of time when I'm iterating on something that doesn't need GUI.  I stick this into a button in my IDE or make a shell alias / bat script to do it.

http://lesterbanks.com/2014/01/maya-using-transfer-attributes-as-a-shrink-wrap-deformer/