np.vstack,np.hstack

import numpy as np

arr1 = np.array([1, 2, 3])
arr2 = np.array([4, 5, 6])
print(np.vstack((arr1, arr2)))
print()

print(np.hstack((arr1, arr2)))
print()

a1 = np.array([[1, 2], [3, 4], [5, 6]])
a2 = np.array([[7, 8], [9, 10], [11, 12]])

print(np.hstack((a1, a2)))

[[1 2 3]
 [4 5 6]]

[1 2 3 4 5 6]

[[ 1  2  7  8]
 [ 3  4  9 10]
 [ 5  6 11 12]]