The Hanning window is a taper formed by using a weighted cosine.
Syntax: numpy.hamming(M) Parameters: M : Number of points in the output window. Returns: AN array
The window, with the maximum value normalized to one (the value one appears only if M is odd).
Code #1:
import numpy as np print(np.hanning(12)) |
Output:
[ 0. 0.07937323 0.29229249 0.57115742 0.82743037 0.97974649 0.97974649 0.82743037 0.57115742 0.29229249 0.07937323 0. ]
Code #2: Plotting the window and its frequency response (requires SciPy and matplotlib).
import numpy as np import matplotlib.pyplot as plt from numpy.fft import fft, fftshift window = np.hanning(51) plt.plot(window) plt.title("Hann window") plt.ylabel("Amplitude"") plt.xlabel("Sample") plt.show() |
Output:
For frequency:
import numpy as np import matplotlib.pyplot as plt from numpy.fft import fft, fftshift window = np.hanning(51) plt.figure() A = fft(window, 2048) / 25.5mag = np.abs(fftshift(A)) freq = np.linspace(-0.5, 0.5, len(A)) response = 20 * np.log10(mag) response = np.clip(response, -100, 100) plt.plot(freq, response) plt.title("Frequency response of Hanning window") plt.ylabel("Magnitude [dB]") plt.xlabel("Normalized frequency [cycles per sample]") plt.axis("tight") plt.show() |
Output:
