Multi-level defaultdict with variable depth?

Question

I have a large list like:

[A][B1][C1]=1 [A][B1][C2]=2 [A][B2]=3 [D][E][F][G]=4 

I want to build a multi-level dict like:

A --B1 -----C1=1 -----C2=1 --B2=3 D --E ----F ------G=4 

I know that if I use recursive defaultdict I can write table[A][B1][C1]=1, table[A][B2]=2, but this works only if I hardcode those insert statement.

While parsing the list, I don't how many []'s I need beforehand to call table[key1][key2][...].

Answer 1

You can do it without even defining a class:

from collections import defaultdict  nested_dict = lambda: defaultdict(nested_dict) nest = nested_dict()  nest[0][1][2][3][4][5] = 6 

Answer 2

Your example says that at any level there can be a value, and also a dictionary of sub-elements. That is called a tree, and there are many implementations available for them. This is one:

from collections import defaultdict class Tree(defaultdict):     def __init__(self, value=None):         super(Tree, self).__init__(Tree)         self.value = value  root = Tree() root.value = 1 root['a']['b'].value = 3 print root.value print root['a']['b'].value print root['c']['d']['f'].value 

Outputs:

1 3 None 

You could do something similar by writing the input in JSON and using json.load to read it as a structure of nested dictionaries.