Example of Haar Mother Wavelet in python using np.piecewise interval definition.

haar_mother_wavelet.py

"""
Haar Mother Wavelet.
Example of Haar Mother Wavelet in python using np.piecewise interval definition.
"""
# Ref.: 
# https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.piecewise.html
# https://sfalsharif.wordpress.com/2009/12/18/piecwise-function-definitions-in-numpy/
import numpy as np
import matplotlib.pyplot as plt

t = 1
x = np.arange(-2, 2, 0.1)
y = np.piecewise(x,
    [(x>=0) & (x < t/2), (x>= t/2) & (x < t)],
    [lambda x: 1, lambda x: -1, lambda x:0])

plt.stem(x,y)