Walsh spectra of 2-ary Boolean functions

# https://en.wikiversity.org/wiki/Equivalence_classes_of_Boolean_functions#Walsh

import numpy as np

bin_walsh = np.array([[0, 0, 0, 0],
                      [0, 1, 0, 1],
                      [0, 0, 1, 1],
                      [0, 1, 1, 0]])

walsh = (bin_walsh * -2) + 1

def int_to_bin_vect(n):
    bin_str = format(n, 'b').zfill(4)[::-1]
    bin_vect = [int(char) for char in bin_str]
    return np.array(bin_vect)

arr_f = np.zeros((0, 4), np.int8)
arr_ws = np.zeros((0, 4), np.int8)
arr_bws = np.zeros((0, 4), np.int8)

for n in range(16):
    f = int_to_bin_vect(n)
    ws = np.dot(f, walsh)
    bws = np.mod(np.dot(f, bin_walsh), 2)

    arr_f   = np.vstack((arr_f  , f  ))
    arr_ws  = np.vstack((arr_ws , ws ))
    arr_bws = np.vstack((arr_bws, bws))

print(arr_f)
print(arr_ws)
print(arr_bws)