嵌套默认字典计数值

Question

I've got a defaultdict with a nested dictionary from which I'm trying to get the sum of the values. But I've been struggling to find a way to do this.

In the example below, I'm trying to count all the count values:

from collections import defaultdict

x = defaultdict(dict)

x['test1']['count'] = 14
x['test4']['count'] = 14
x['test2']['count'] = 14
x['test3']['count'] = 14

print x

""" methods I've tried """

# print x.values()
# print sum(x for y in x.values() for x in y['count'].iteritems())
# print sum(x.itervalues())

The methods above that I've tried (in many different variations) didn't provide the desired results.

Any clues or assistance as to where I may be in error?

Answer 1

只需求sum(x[k]['count'] for k in x) 。

Answer 2

If you have to caluculate sum of just 'count' key, you may do:

>>> sum(y['count'] for y in x.values())
56

If there is a possibility of having other keys as well (apart from 'count'), and you want to calculate sum of all the values, then you have to do:

>>> sum(z for y in x.values() for z in y.values())
56

# OR,
# import itertools
# sum(itertools.chain(*[y.values() for y in x.values()]))

Answer 3

If you want to sum the values of all sub dictionaries, sum twice:

>>> sum(sum(y.values()) for y in x.values())
56