create a two by two matrix numpy code example

Example: join two numpy 2d array

import numpy as np

a = np.array([[0, 1, 3], [5, 7, 9]])
b = np.array([[0, 2, 4], [6, 8, 10]])
c = np.concatenate((a, b), axis=0)
print(c)

Output : 
[[ 0  1  3]
 [ 5  7  9]
 [ 0  2  4]
 [ 6  8 10]]