10 December, 2011

Some python goodies

I love coding in python and every time I work with it I feel enthusiastic about this programming language. While coding it is also exciting to learn new features and figure out what you can do with it. Following are some useful snippets that I am using in my rigging framework. 

1. Assign values from a list that is shorter or longer than the original list
I find this simple function handy since this allows me to assign values from a list that is shorter or longer than the target list. It acts like partial assignment, leaving elements intact in my original list if source list is shorter.
def assignValues(list1, list2):
    mapFunc = lambda a,b: a if b is None else b
    origLen = len(list1)
    list1[:] = map(mapFunc, list1, list2)[:origLen] 

tgtList = [1,2,3,4]
srcList = [0,0]
assignValues(tgtList, srcList)

2. Overriding [] (indexing) in python for 2d indexing We know that we can use __getitem__ to assign an array like behavior (or make object iterable). But how about making object behave like 2 or 3 dimensional array? You can actually pass tuple as a key to __getitem__  and then use unpacking feature of python. I found the following code online on activestate recipe website.
def __getitem__(self, (row, column)):
    return self._data[row][column]

3. Some great recipes on python website Some great code recipes and a very useful module.  http://docs.python.org/library/itertools.html#recipes

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