Reshape a numpy array so the columns wrap below the original rows

Question

Consider the following scenario:

a = np.array([[1,1,1,3,3,3], [2,2,2,4,4,4]])
np.reshape(a, (4, 3))

Output:

array([[1, 1, 1],
       [3, 3, 3],
       [2, 2, 2],
       [4, 4, 4]])

Desired output:

array([[1, 1, 1],
       [2, 2, 2],
       [3, 3, 3],
       [4, 4, 4]])

How can I reshape the array so the rows stay paired together and the overflowing columns wrap below the existing rows?

Answer 1

As I described in the comments. You can combine that into one statement:

import numpy as np
a = np.array([[1,1,1,3,3,3], [2,2,2,4,4,4]])

a1 = a[:,:3]
a2 = a[:,3:]
a3 = np.concatenate((a1,a2))
print(a3)

Output:

[[1 1 1]
 [2 2 2]
 [3 3 3]
 [4 4 4]]