如何从以元组为键的字典中制作以整数为键的字典

Question

I have a dictionary in which keys are tuples (pairs):

dictionary1 = {(0, 1): 0, (2, 7): 3, (4, 7): 0, (1, 3): 0} 

(value means how many times does the tuple appear)

I want to transform the dictionary so that each element in the tuple will become key to the new dictionary keeping the same value as in original dict. The structure of my new dictionary should be like:

dictionary2 = {0: 0, 1: 0, 2: 3, 3: 0, 4: 0, 7: 3} 

What is the easiest/most-efficient way to do that? In case tuple value appears at more than one place, the new dict will contain the sum of the values for all the tuple where it exists.

Answer 1

So you're basically looking for a counter. Lucky you, python has one in the collections module:

from collections import Counter

c = Counter()
for k, v in d.items():
    for i in k:
        c[i] += v

Alternatively, with a plain dictionary:

di = {}    
for k,v in d.items():
    for i in k:
        di[i] = di.get(i, 0) + v