Two arguments in __getitem__

Question

I'm creating a Matrix Class in Python and created a __getitem__ method, that gets i and j and return the [i][j] item. So I wrote "def __getitem__(i, j):"
But when I try to use the indexer, (matrix[0, 0]), the interpreter returns TypeError: missing required positional argument j

Answer 1

Levi Oliveira Matias

only one argument is passed to __getitem__, no matter how many arguments you pass into the index. When you pass in more than one argument while indexing, the arguments are passed in as a tuple. For example,
instance[0]
will pass 0 to __getitem__. But
instance[1, 2]
will pass (1, 2), a tuple, to __getitem__.

See this example
https://code.sololearn.com/cg8P87t26Tp8/?ref=app

Answer 2

Do you mean " matrix[0][0] " to get the first element of the first element of a 2dimensional array?

Then your matrix must have self parameter as the first parameter and index as the second parameter:

def __getitem__(self, index):
return Matrix.array[index]

Take a look at this for example:
https://code.sololearn.com/ca13A15a22a8