how to make an array of repeating series of elements numpy code example

Example: numpy array with 2 times each value

>>> np.repeat(3, 4)
array([3, 3, 3, 3])

>>> x = np.array([1,2,3,4])
>>> np.repeat(x, 2)
array([1, 1, 2, 2, 3, 3, 4, 4])