Numpy

import numpy as np
a = np.array([[1,2,3,4], [5,6,7,8], [9,10,11,12]])
col_r1 = a[:, 1]
col_r2 = a[:, 1:2]
print(col_r1, col_r1.shape)  # Prints "[ 2  6 10] (3,)"
print(col_r2, col_r2.shape)  # Prints "[[ 2]
                              #          [ 6]
                              #          [10]] (3, 1)"
print(a[[0, 0], [1, 1]])  # Prints "[2 2]"

 

x = np.array([[1,2],[3,4]])
print(np.sum(x, axis=0))  # Compute sum of each column; prints "[4 6]"
print(np.sum(x, axis=1))  # Compute sum of each row; prints "[3 7]"