Updating nested dictionaries when data has existing key

Question

I am trying to update values in a nested dictionary, without over-writting previous entries when the key already exists. For example, I have a dictionary:

Answer 1

You can use collections.defaultdict for this, and just set the key-value pairs within the nested dictionary.

from collections import defaultdict
my_dict = defaultdict(dict)
my_dict['myKey']['nestedDictKey1'] = a_value
my_dict['myKey']['nestedDictKey2'] = another_value

Alternatively, you can also write those last 2 lines as

my_dict['myKey'].update({"nestedDictKey1" : a_value })
my_dict['myKey'].update({"nestedDictKey2" : another_value })