So I was given a worksheet exercise as follows: Given the following grid of 25 values, extract the central 3 x 3 sub-grid of 9 s from the larger grid using the split() function: 1 2 3 4 5 1 9 9 9 5 1 9 9 9 5 1 9 9 9 5 1 2 3 4 5 And the solution is as follows: x = np.array([[1,2,3,4,5], [1, 9, 9, 9, 5], [1, 9, 9, 9, 5], [1, 9, 9, 9, 5], [1, 2, 3, 4, 5]]) x1, x2, x3 = np.split(x, [1, 4]) y1, y2, y3 = np.split(x2, [1, 4], axis = 1) print(y2) My question is, why is it [1, 4] in the brackets? does this refer to the element number, if so, should it not be [1, 3]? Sorry if this seems like a very simple question - am still super new to coding!! Thanks in advance :) source https://stackoverflow.com/questions/74524188/understanding-numpy-split-function-to-extract-sub-grid