Concatenate Two One-dimensional To Two Columns Array

a = np.array([1, 2, 3]) aa = np.array([1], [2], [3]) b = np.array([1, 2, 3]) bb = np.array([1], [2], [3]) np.concatenate((a, b), axis = 1) array([1, 2, 3, 1, 2, 3]) # It's ok,

Solution 1:

Note that a and b are both one-dimensional; there's no axis 1 to concatenate along. You want vstack:

>>>import numpy as np>>>a = np.array([1,2,3])>>>b = a.copy()>>>np.vstack([a,b])
array([[1, 2, 3],
       [1, 2, 3]])

Alternatively, you could reshape a and b first:

>>> np.concatenate([a[np.newaxis,:],b[np.newaxis,:]],axis = 0)
array([[1, 2, 3],
       [1, 2, 3]])