Question

I would like to slice a numpy array to obtain the i-th index in the last dimension. For a 3D array, this would be:

slice = myarray[:, :, i]

But I am writing a function where I can take an array of arbitrary dimensions, so for a 4D array I’d need myarray[:, :, :, i], and so on. Is there a way I can obtain this slice for any array without explicitly having to write the array dimensions?

Answer 1

There is ... or Ellipsis, which does exactly this:

slice = myarray[..., i]

Ellipsis is the python object, if you should want to use it outside the square bracket notation.