python - Indexing nested list by a list

Question

given a nested list like

>>> m= [[3, 1], [2, 7]]

I can get an element like this

>>> m[1][0]
2

How can i get the same value if the index is given in a list, i.e. as [1, 0]?

I am looking for something that the Q programming language offers with dot like in code below

q) m: (3 1; 2 7)
q) m[1][0]
2
q) m . 1 0
2

Answer 1

As a quick-n-dirty solution, you can abuse functools.reduce like this:

from functools import reduce
def get_recursive(lst, idx_list):
    return reduce(list.__getitem__, [lst, *idx_list])

>>> y = [[3, 1], [2, 7]]
>>> get_recursive(y, [0, 1])
1
>>> get_recursive(y, [1, 0])
2

There are quite a few corner cases to handle (plus you'd have to be sure the path exists or else handle any errors that arise) but this should get you started.