Merge two dictionaries that have dictionaries as key values

Question

Merge two dictionaries of dictionaries

My question is similar to this one, but the answers don't produce the right result (for me?).

Take these dictionaries:

a = {'a': {'a': 1}}
b = {'a': {'b': 2}}

I want to produce:

c = {'a': {'a': 1, 'b': 2}}

Using the answers from the quoted question, these all produce:

c = a.copy()
c.update(b)

>>
c == {'a': {'b': 2}

Consider that a and b might be more complex than this, for example:

a = {'a': {'aa': {'aaa': 1}, 'bb': {'bbb': 2}}}
b = {'a': {'bb': {'aaa': 1}, 'bb': {'bbb': 2}}}

Answer 1

In this case you can use

>>> a['a'].update(b['a'])
>>> a
{'a': {'a': 1, 'b': 2}}

Element in dictionary is also dictionary, so you can treat that element as dictionary. As for more complex example I don't know what result should be. But in general, you can access elements in element as dictionary in nested for loops.