Vectorize numpy array expansion

Question

I\'m trying to find a way to vectorize an operation where I take 1 numpy array and expand each element into 4 new points. I\'m currently doing it with Python loop. First l

Answer 1

For the first example, you can use np.kron

>>> a = np.array([0, 1, 1, 0])
>>> np.kron(input_array, a)
array([0, 1, 1, 0, 0, 2, 2, 0, 0, 3, 3, 0, 0, 4, 4, 0])

For the second example, you can use np.repeat and np.tile

>>> b = np.array([-0.2, -0.2, 0.2, 0.2])
>>> np.repeat(input_array, b.size) + np.tile(b, input_array.size)
array([ 0.8,  0.8,  1.2,  1.2,  1.8,  1.8,  2.2,  2.2,  2.8,  2.8,  3.2,
        3.2,  3.8,  3.8,  4.2,  4.2])