Question

I would like to build a multi-level dictionary such like:

A = { 
    'a': {
        'A': {
            '1': {}, 
            '2': {}, 
        },  
        'B': {
            '1': {}, 
            '2': {}, 
        },  
    },  
    'b': {
        'A': {
            '1': {}, 
            '2': {}, 
        },  
        'B': {
            '1': {}, 
            '2': {}, 
        },  
    },  
}

My question is that whether it existed a function that I can build the above diction by:

D = function(['a', 'b'], ['A', 'B'], ['1', '2'], {})

Answer 1

This uses the copy function to allow you specify a different leaf node. Otherwise all the leaves will point to the same dictionary.

from copy import copy

def multidict(*args):
    if len(args) == 1:
        return copy(args[0])
    out = {}
    for x in args[0]:
        out[x] = multidict(*args[1:])
    return out

print multidict(['a', 'b'], ['A', 'B'], ['1', '2'], {})