Apply a length-k median filter to a 1D array x

Medianfilter.py

import numpy as np
import cv2 as cv

def medianFilter(x, k):
    """
        Apply a length-k median filter to a 1D array x.
        Boundaries are extended by repeating endpoints.
        this is the equivalent of opencv Median for 2D array
    """
    if k == 1 :
        return x
    assert k % 2 == 1, "Median filter length must be odd."
    assert x.ndim == 1, "Input must be one-dimensional."
    k2 = (k - 1) // 2
    y = np.zeros ((len (x), k), dtype=x.dtype)
    y[:,k2] = x

    for i in range (k2):
        j = k2 - i
        y[j:,i] = x[:-j]
        y[:j,i] = x[0]
        y[:-j,-(i+1)] = x[j:]
        y[-j:,-(i+1)] = x[-1]

    return np.median (y, axis=1)


x = np.array([5, 7, 6, 8, 7, 9, 8, 8, 7, 9, 7, 5, 4, 5, 4, 3, 2, 1, 0]).astype(np.uint8)
print(medianFilter(x, 5))
print(cv.medianBlur(np.asarray([x]), 5)[0])