Insert N zeros between elements of array

Question

Consider the following array h_0 = (1/16)*np.array([1,4,6,4,1]) . What is the easiest way to insert N zeros between each values of h_0 (as part of a function)? So that I get for N=2 for example

>>> array([0.0625, 0.    , 0.    , 0.25  , 0.    , 0.    , 0.375 , 0.    ,
       0.    , 0.25  , 0.    , 0.    , 0.0625])

Answer 1

The simplest is probably slicing:

h_0 = (1/16)*np.array([1,4,6,4,1])
N = 2

out = np.zeros(h_0.size * (N+1) - N , h_0.dtype)
out[::N+1] = h_0
out
# array([0.0625, 0.    , 0.    , 0.25  , 0.    , 0.    , 0.375 , 0.    ,
#        0.    , 0.25  , 0.    , 0.    , 0.0625])

Answer 2

Reshape h_0 to 2D, stack it with zeros and then flatten the result:

import numpy as np

h_0 = (1/16)*np.array([1,4,6,4,1])

N = 2
zeros = np.zeros((h_0.shape[0], N))

print(np.hstack((h_0[:,None], zeros)).reshape(-1)[:-N])
# [0.0625 0. 0. 0.25 0. 0. 0.375 0. 0. 0.25 0. 0. 0.0625]

You can play with this here .