How to find common keys in a list of dicts and sort them by value?

Question

I want to create a finalDic which contains common keys and sum of their values

myDic = [{2:1, 3:1, 5:2}, {3:4, 6:4, 2:3}, {2:5, 3:6}, ...]

First find common keys

commonkey = [{2:1, 3:1}, {2:3, 3:4}, {2:5, 3:6}]

Then Sum and sort by their values

finalDic= {3:11, 2,9}

I've tried this and not even close what i want

import collections

myDic = [{2:1, 3:1, 5:2}, {3:4, 6:4, 2:3}, {2:5, 3:6}]

def commonKey(x):
    i=0
    allKeys = []
    while i<len(x):
        for key in x[0].keys():
            allKeys.append(key)
        i=i+1
    commonKeys = collections.Counter(allKeys)
    commonKeys = [i for i in commonKeys if commonKeys[i]>len(x)-1]
    return commonKeys

print commonKey(myDic)

Thanks

Answer 1

Here's how I'd do it:

my_dict = [{2:1, 3:1, 5:2}, {3:4, 6:4, 2:3}, {2:5, 3:6}]

# Finds the common keys
common_keys = set.intersection(*map(set, my_dict))

# Makes a new dict with only those keys and sums the values into another dict
summed_dict = {key: sum(d[key] for d in my_dict) for key in common_keys}

Or as a crazy one-liner:

{k: sum(d[k] for d in my_dict) for k in reduce(set.intersection, map(set, my_dict))}