Creating a nested dictionary from a flattened dictionary

Question

I have a flattened dictionary which I want to make into a nested one, of the form

flat = {\'X_a_one\': 10,
        \'X_a_two\': 20, 
        \'X_b_one\': 10,         


        

Answer 1

The other answers are cleaner, but since you mentioned recursion we do have other options.

def nest(d):
    _ = {}
    for k in d:
        i = k.find('_')
        if i == -1:
            _[k] = d[k]
            continue
        s, t = k[:i], k[i+1:]
        if s in _:
            _[s][t] = d[k]
        else:
            _[s] = {t:d[k]}
    return {k:(nest(_[k]) if type(_[k])==type(d) else _[k]) for k in _}