Question

I am looking for a Pythonic way (the less code possible) to unite the content of two dictionnaries :

basket1 = {"ham":2,"eggs":3}
basket2 = {"eggs":4,"spam":1}

I want to get a third basket that is going to be the “sum” of the two other, basket 3 should be:

basket3 --> {"ham":2,"eggs":7,"spam":1}

If possible, doing this using set

Answer 1

I’d use a Counter, which is a kind of defaultdict with some nice properties:

>>> from collections import Counter
>>> basket1 = {"ham":2,"eggs":3}
>>> basket2 = {"eggs":4,"spam":1}
>>> basket_sum = Counter(basket1) + Counter(basket2)
>>> basket_sum
Counter({'eggs': 7, 'ham': 2, 'spam': 1})

which you could convert back into a pure dict if you wanted:

>>> dict(basket_sum)
{'eggs': 7, 'ham': 2, 'spam': 1}