I want to traverse a nested list and find index of that list

Question

I want to traverse over the nested list below, search for a number and then print the index value of that entire list, i.e: my_foo(lst=[1, 3, 'Test', 5, 7], number=3) returns 1.

This is my list:

my_list = [['Hello', 'World','!'], [1, 3, 'Test', 5, 7], [2, 4]]

I want to search for example 1, and if that's True, print its list index.

Answer 1

Here is a function that takes a list and a function as a key:

from typing import List, Callable

my_list = [['Hello', 'World','!'],[1, 3, 'Test', 5, 7],[2, 4]]


def nested_index(l: List, key: Callable[[List], bool]):
    for i, v in enumerate(l):
        if key(v):
            return i
    raise ValueError

Example:

nested_index(my_list, lambda l: 1 in l) -> 1
nested_index(my_list, lambda l: "hello" in l) -> 0
nested_index(my_list, lambda l: "foo" in l) -> ValueError