Python dictionary increment

Question

In Python it\'s annoying to have to check whether a key is in the dictionary first before incrementing it:

if key in my_dict:
  my_dict[key] += num
else:
  m         


        

Answer 1

You have quite a few options. I like using Counter:

>>> from collections import Counter
>>> d = Counter()
>>> d[12] += 3
>>> d
Counter({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
>>> d
defaultdict( at 0x7ff2fe7d37d0>, {12: 3})