Python Index Nested Dictionary with List

Question

If I have a nested dictionary and varying lists:

d = {'a': {'b': {'c': {'d': 0}}}}
list1 = ['a', 'b']
list2 = ['a', 'b', 'c']
list3 = ['a', 'b', 'c', 'd']

How can I access dictionary values like so:

>>> d[list1]
{'c': {'d': 0}}
>>> d[list3]
0

while not a strict duplicate, this is a close match: https://stackoverflow.com/q/31033549/758174 — Pierre D, Oct 12 '22 at 20:14

Lucas M. Uriarte · Accepted Answer · 2022-10-12T21:25:31.677

6

you can use functools reduce. info here. You have a nice post on reduce in real python

from functools import reduce

reduce(dict.get, list3, d)
>>> 0

EDIT: mix of list and dictioanries

in case of having mixed list and dictionary values the following is possible

d = {'a': [{'b0': {'c': 1}}, {'b1': {'c': 1}}]}
list1 = ['a', 1, 'b1', 'c']

fun = lambda element, indexer: element[indexer]
reduce(fun, list1, d)
>>> 1

edited Oct 12 '22 at 21:25

answered Oct 12 '22 at 20:11

Lucas M. Uriarte

2,403
5
19

This is a great answer. But I realize it doesn't work if you have lists in your dictionary like so `d = {'a': [{'b0': {'c': 1}}, {'b1': {'c': 1}}]}` and a list like so `['a', 1, 'c']` – Oliver Oct 12 '22 at 21:08
1

It is possible let me make an edit – Lucas M. Uriarte Oct 12 '22 at 21:09
1

actually is possible if your list is as follow ['a', 1, 'b1' 'c'], would that pass? In any case I have added an edit – Lucas M. Uriarte Oct 12 '22 at 21:15
legendary ..... – Oliver Oct 12 '22 at 21:22
you can check the real python post whenever you have time, is quite nice, reduce can be very useful! – Lucas M. Uriarte Oct 12 '22 at 21:24

score 2 · Answer 2 · answered Oct 12 '22 at 20:13

2

Use a short function:

def nested_get(d, lst):
    out = d
    for x in lst:
        out = out[x]
    return out

nested_get(d, list1)
# {'c': {'d': 0}}

answered Oct 12 '22 at 20:13

mozway

194,879
13
39
75

Python Index Nested Dictionary with List

2 Answers2