Python3 | classes | OOP

Question

class Foo:
    """
    class to represent 2D arrays
    """
    def __init__(self, lst: list[list]) -> None:
        self.lst = lst

a_list = [
    [1, 2, 3, 4],
    [5, 6, 7, 8],
    [9, 10, 100]
]

If I want to access 10 in my variable a_list. I type a_list[2][1]

What I am trying to do here is ...

I create an instance i.e Foo(a_list) and save it in a variable n. So, n = Foo(a_list) is what I type. Now, if I again want to access 10. I surely can access it by n.lst[2][1]

My question here, is there anyway I can do the same thing the following way: n[2][1] ?

azro · Accepted Answer · 2021-08-04 09:05:51Z

1

This can be done using the __getitem__ method. Something like

class Foo:
    """
    class to represent 2D arrays
    """
    def __init__(self, lst: list[list]) -> None:
        self.lst = lst

    def __getitem__(self, idx):
        return self.lst[idx]

For your example, n[2] returns a list, so n[2][1] is indexing into a 'normal' python list.

edited Aug 4, 2021 at 9:05

azro

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answered Aug 4, 2021 at 8:57

Holloway

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