Counter for items in lists in lists?

[Michael Hoffman]

If you want to be able to use any iterable, you can use itertools.chain().

 >>> import itertools
 >>> myList=[['a','b','c','d'],['a','f','g','h'],['a','b','x','y']]
 >>> counts = {}
 >>> for item in itertools.chain(*myList):
...     counts[item] = counts.get(item, 0) + 1
...
 >>> counts
{'a': 3, 'c': 1, 'b': 2, 'd': 1, 'g': 1, 'f': 1, 'h': 1, 'y': 1, 'x': 1}
--
Michael Hoffman