How to make a getitem method that allows list[][] indexing (2D)

Question

I am trying to make a getitem method where I can use [][] to get an element from and array I have made. The method I came across is this:

def __getitem__(self, item):
        x, y = item 
        return self.twoDim[x][y]

The problem with this is that I only can access the array by using a tuple, like array[1,0]. What I want is to be able to do this: array[1][0].

Im not sure how to pass these two arguments inside the getitem method since it only can take one at a time.

Any tips on how to make it work? Thank you 🙂

Asked By: ili

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Source

Answer 1

In Python, two pairs of square brackets mean twice indexes, so array[1][0] is equivalent to:

array.__getitem__(1).__getitem__(0)

After one index, your twoDim can return the object that can be indexed again, so if the index has only one element, you can apply it to twoDim directly:

def __getitem__(self, item):
    if not isinstance(item, tuple):
        return self.twoDim[item]
    x, y = item
    return self.twoDim[x][y]

Answered By: Mechanic Pig

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