Combining two dictionaries into one with the same keys?

Question

I\'ve looked through a few of the questions here and none of them seem to be exactly my problem. Say I have 2 dictionaries, and they are dict1

{\'A\': 25 ,          


        

Answer 1

I just needed to combine an unknown number dictionaries and after seeing answers to this question came up with more universal solutions:

1) dictionaries of values:

dic1 = {'A': 1, 'B': 1, 'C': 1}
dic2 = {'A': 2, 'B': 2, 'C': 2}
dic3 = {'D': 3, 'E': 3, 'F': 3}

def combineDictVal(*args):
    result = {}
    for dic in args:
        for key in (result.viewkeys() | dic.keys()):
            if key in dic:
                result.setdefault(key, []).append(dic[key])
    return result

print combineDictVal(dic1, dic2, dic3)

Result: {'A': [1, 2], 'C': [1, 2], 'B': [1, 2], 'E': [3], 'D': [3], 'F': [3]}

2) dictionaries of lists (difference is in append/extend*):

dic1 = {'A': [1, 2], 'B': [1, 2], 'C': [1, 2]}
dic2 = {'A': [3, 4], 'B': [3, 4], 'C': [3, 4]}
dic3 = {'D': [5, 6], 'E': [5, 6], 'F': [5, 6]}

def combineDictList(*args):
    result = {}
    for dic in args:
        for key in (result.viewkeys() | dic.keys()):
            if key in dic:
                result.setdefault(key, []).extend(dic[key])
    return result

print combineDictList(dic1, dic2, dic3)

Result: {'A': [1, 2, 3, 4], 'C': [1, 2, 3, 4], 'B': [1, 2, 3, 4], 'E': [5, 6], 'D': [5, 6], 'F': [5, 6]}

3) Universal for int / lists:

dic1 = {'A': 1, 'B': 1, 'C': [1, 1]}
dic2 = {'A': 2, 'B': [2, 2], 'C': 2}
dic3 = {'D': 3, 'E': 3, 'F': [3, 3]}

def combineDict(*args):
    result = {}
    for dic in args:
        for key in (result.viewkeys() | dic.keys()):
            if key in dic:
                if type(dic[key]) is list:
                    result.setdefault(key, []).extend(dic[key])
                else:
                    result.setdefault(key, []).append(dic[key])
    return result

print combineDict(dic1, dic2, dic3)

Result:

{'A': [1, 2], 'C': [1, 1, 2], 'B': [1, 2, 2], 'E': [3], 'D': [3], 'F': [3, 3]}

These solutions are not the fastest possible, however they are clear and work just fine. Hope it will help someone.