Multiple levels of 'collection.defaultdict' in Python
- by Morlock
Thanks to some great folks on SO, I discovered the possibilities offered by collections.defaultdict, notably in readability and speed. I have put them to use with success.
Now I would like to implement three levels of dictionaries, the two top ones being defaultdict and the lowest one being int. I don't find the appropriate way to do this. Here is my attempt:
from collections import defaultdict
d = defaultdict(defaultdict)
a = [("key1", {"a1":22, "a2":33}),
("key2", {"a1":32, "a2":55}),
("key3", {"a1":43, "a2":44})]
for i in a:
d[i[0]] = i[1]
Now this works, but the following, which is the desired behavior, doesn't:
d["key4"]["a1"] + 1
I suspect that I should have declared somewhere that the second level defaultdict is of type int, but I didn't find where or how to do so.
The reason I am using defaultdict in the first place is to avoid having to initialize the dictionary for each new key.
Any more elegant suggestion?
Thanks pythoneers!
