Setting a value in a nested python dictionary given a list of indices and value

I took the freedom to extend the code from the answer of Bakuriu. Therefore upvotes on this are optional, as his code is in and of itself a witty solution, which I wouldn't have thought of.

def nested_set(dic, keys, value, create_missing=True):
    d = dic
    for key in keys[:-1]:
        if key in d:
            d = d[key]
        elif create_missing:
            d = d.setdefault(key, {})
        else:
            return dic
    if keys[-1] in d or create_missing:
        d[keys[-1]] = value
    return dic

When setting create_missing to True, you're making sure to only set already existing values:

# Trying to set a value of a nonexistent key DOES NOT create a new value
print(nested_set({"A": {"B": 1}}, ["A", "8"], 2, False))
>>> {'A': {'B': 1}}

# Trying to set a value of an existent key DOES create a new value
print(nested_set({"A": {"B": 1}}, ["A", "8"], 2, True))
>>> {'A': {'B': 1, '8': 2}}

# Set the value of an existing key
print(nested_set({"A": {"B": 1}}, ["A", "B"], 2))
>>> {'A': {'B': 2}}

Here's another option:

from collections import defaultdict
recursivedict = lambda: defaultdict(recursivedict)
mydict = recursivedict()

I originally got this from here: Set nested dict value and create intermediate keys.

It is quite clever and elegant if you ask me.

Something like this could help:

def nested_set(dic, keys, value):
    for key in keys[:-1]:
        dic = dic.setdefault(key, {})
    dic[keys[-1]] = value

And you can use it like this:

>>> d = {}
>>> nested_set(d, ['person', 'address', 'city'], 'New York')
>>> d
{'person': {'address': {'city': 'New York'}}}