Loop creating nested dicts

Question

I'm importing data from CSV and placing it in nested dicts. My current key-checking looks like this:

data = {}
[...]
if day not in data:
    data[day] = {}
if hour not in data[day]:
    data[day][hour] = {}
if user in data[day][hour]:
    worked_time += (
        data[day][hour][user]['worked_time']
    )
data[day][hour][user] = {
    'name': users[user]['name'],
    'worked_time': worked_time
}

They can be several users for each data[day][hour]
Was wondering if there's better way for checking if each key exists than using several ifs.

I don't think `'name': [users][user]['name'],` is valid python syntax. But `collections.defaultdict` or `dict.setdefault` may be good alternatives to these `if xxx not in yyy` statements. — MSeifert, Dec 29 '16 at 14:53
this should answer your questions: https://stackoverflow.com/questions/19189274/defaultdict-of-defaultdict-nested#19189356 — hiro protagonist, Dec 29 '16 at 14:54
You're right sir, that's my misspelling, should be `users[user]['name]`. Will check linked answer, thank you. — Pythonist, Dec 29 '16 at 14:56

wildwilhelm · Accepted Answer · 2016-12-29T14:59:21.863

-2

collections.defaultdict is nice. If a dict doesn't have a value for the key you specify, it creates a new one for you.

from collections import defaultdict
data = defaultdict(lambda: defaultdict(lambda: defaultdict(dict)))
data['day']['hour']['user']['worked_time'] = 2

edited Dec 29 '16 at 14:59

answered Dec 29 '16 at 14:53

wildwilhelm

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Thank you, it works, and your edited answer is way better than the first one. – Pythonist Dec 29 '16 at 15:07

Loop creating nested dicts

1 Answers1