How can I combine dictionaries with the same keys?

Question

I have a list of dictionaries like so:

dicts = [
    {\'key_a\': valuex1,
     \'key_b\': valuex2,
     \'key_c\': valuex3},

    {\'key_a\': valuey1,
     \         


        

Answer 1

If all the dicts have the same set of keys, this will work:

dict((k, [d[k] for d in dictList]) for k in dictList[0])

If they may have different keys, you'll need to first built a set of keys by doing set unions on the keys of the various dicts:

allKeys = reduce(operator.or_, (set(d.keys()) for d in dictList), set())

Then you'll need to protect against missing keys in some dicts:

dict((k, [d[k] for d in [a, b] if k in d]) for k in allKeys)