#!/usr/bin/env python3

import numpy as np

# Create 4x3 matrix
matrix = np.array([[1, 2, 3], 
                   [4, 5, 6],
                   [7, 8, 9],
                   [10, 11, 12]])

# Reshape matrix into 2x6 matrix
new_matrix=matrix.reshape(2, 6)
print(new_matrix)
# [[ 1  2  3  4  5  6]
# [ 7  8  9 10 11 12]]