import numpy as np

mat_A = np.random.randn(12, 4)

# transpose — the manual, honest way
mat_A_T = np.zeros((4, 12))
for i in range(mat_A.shape[0]):
    for j in range(mat_A.shape[1]):
        mat_A_T[j, i] = mat_A[i, j]

print(mat_A_T)

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