How to update values in nested dictionary if keys are in a list? [duplicate]

Answer 1

You can iteratively build/access levels using setdefault in a loop:

d = {}
d2 = d
for k in key_lst[:-1]:
    d2 = d2.setdefault(k, {})

d2[key_lst[-1]] = value
print(d)
# {'key1': {'key2': {'key3': 'my_value'}}}

d is the reference to your dictionary, and d2 is a throw-away reference that accesses inner levels at each iteration.