An alternative solution for Q.70

[iamyifan]

70. Consider the vector [1, 2, 3, 4, 5], how to build a new vector with 3 consecutive zeros interleaved between each value? (★★★) hint: array[::4]

# Author: Warren Weckesser

Z = np.array([1,2,3,4,5])
nz = 3
Z0 = np.zeros(len(Z) + (len(Z)-1)*(nz))
Z0[::nz+1] = Z
print(Z0)

A more readable function from numpy: numpy.insert(arr, obj, values, axis=None). NumPy Doc

Thus, an alternative solution will be:

Z = np.array([1, 2, 3, 4, 5])
Z0 = np.insert(a[..., np.newaxis], [1], [[0, 0, 0] for  _ in range(len(a))], axis=1)
Z0 = Z0.flatten()[:-3]
print(Z0)

[heyzwming]

您好，您的邮件我已收到，我会尽快回复您。

[rougier]

@Jeff1999 Thansk. Did you time the two solutions ? I'm not too confident with the for loop and a big array.