How to make a nested dictionary in Python 3

This function creates a nested dictionary with an assigned value type for the deepest level subkeys. Thoug I use this function for many years, I am not an author of it.

from collections import defaultdict

def autovivify(levels=1, final=dict):
    return (defaultdict(final) if levels < 2 else
            defaultdict(lambda: autovivify(levels - 1, final)))

Posted Mon 05 May 2025, last updated Mon 05 May 2025 by aekazakov in Python (recipes, Python)