Python dictionary increment
You have quite a few options. I like using Counter:
>>> from collections import Counter>>> d = Counter()>>> d[12] += 3>>> dCounter({12: 3})Or defaultdict:
>>> from collections import defaultdict>>> d = defaultdict(int) # int() == 0, so the default value for each key is 0>>> d[12] += 3>>> ddefaultdict(<function <lambda> at 0x7ff2fe7d37d0>, {12: 3})
What you want is called a defaultdict
See http://docs.python.org/library/collections.html#collections.defaultdict