How to add an extra column to a NumPy array

Question

Let’s say I have a NumPy array, a:

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

And I would like to add a column of ze

Answer 1

In my case, I had to add a column of ones to a NumPy array

X = array([ 6.1101, 5.5277, ... ])
X.shape => (97,)
X = np.concatenate((np.ones((m,1), dtype=np.int), X.reshape(m,1)), axis=1)

After X.shape => (97, 2)

array([[ 1. , 6.1101],
       [ 1. , 5.5277],
...