Flatten nested dictionaries, compressing keys

Question

Suppose you have a dictionary like:

{\'a\': 1,
 \'c\': {\'a\': 2,
       \'b\': {\'x\': 5,
             \'y\' : 10}},
 \'d\': [1, 2, 3]}

Ho

Answer 1

here's a solution using a stack. No recursion.

def flatten_nested_dict(nested):
    stack = list(nested.items())
    ans = {}
    while stack:
        key, val = stack.pop()
        if isinstance(val, dict):
            for sub_key, sub_val in val.items():
                stack.append((f"{key}_{sub_key}", sub_val))
        else:
            ans[key] = val
    return ans