add columns at start in numpy array code example

Example 1: add column to existing numpy array

b = np.insert(a, insert_index, values=a[:,2], axis=1)

Example 2: add a new column to numpy array

import numpy as np
N = 10
a = np.random.rand(N,N)
b = np.zeros((N,N+1))
b[:,:-1] = a