arr=np.array([4,7,12])
arr1=np.array([5,9,15])
np.concatenate((arr,arr1))
# Must give array([ 4, 7, 12, 5, 9, 15])
np.concatenate((arr,arr1),axis=1)
#Must give
#[[4,5],[7,9],[12,15]]
# but it gives *** numpy.AxisError: axis 1 is out of bounds for array of dimension 1