I'm implementing Strassen's Matrix Multiplication using python. In divide step, we divide a larger matrix into smaller sub-matrices. Is there a built-in numpy function to split a matrix?
According to this answer, you might use the swapaxes
:
You can create a helper method as:
def split(array, nrows, ncols):
"""Split a matrix into sub-matrices."""
r, h = array.shape
return (array.reshape(h//nrows, nrows, -1, ncols)
.swapaxes(1, 2)
.reshape(-1, nrows, ncols))
Here is an example of using it
import numpy as np
array = np.array([
[1, 1, 2, 2],
[3, 3, 4, 4],
[5, 5, 6, 6],
[7, 7, 8, 8]])
A, B, C, D = split(array, 2, 2)
# A =
# [[1 1]
# [3 3]]
# B =
# [[2 2]
# [4 4]]
# C =
# [[5 5]
# [7 7]]
# D =
# [[6 6]
# [8 8]]
print('A = \n{}\n\n'
'B = \n{}\n\n'
'C = \n{}\n\n'
'D =\n{}'.format(A, B, C, D))