Join multiple dicts to create new list with value as list of values of original dict

Question

I\'m on Python 2.7 and have looked at several solutions here which works if you know how many dictionaries you are merging, but I could have anything between 2 to 5.

I

Answer 1

Use a defaultdict:

In [18]: def gen_dictionaries():
    ...:     yield {'key1': 1, 'key2': 2, 'key3': 3}
    ...:     yield {'key1': 4, 'key2': 5, 'key3': 6}
    ...:

In [19]: from collections import defaultdict

In [20]: final = defaultdict(list)

In [21]: for d in gen_dictionaries():
    ...:     for k, v in d.iteritems():
    ...:         final[k].append(v)
    ...:

In [22]: final
Out[22]: defaultdict(list, {'key1': [1, 4], 'key2': [2, 5], 'key3': [3, 6]})