fast_fourier_transform.py

"""example of fast Fourier transform from I don't remember where"""
import numpy as np
import matplotlib.pyplot as plt
from scipy.fftpack import fft

N = 600

T = 1.0 / 800.0
x = np.linspace(0.0, N * T, N)
y = np.sin(50.0 * 2.0 * np.pi * x) + 0.5 * np.sin(80.0 * 2.0 * np.pi * x)
yf = fft(y)
xf = np.linspace(0.0, 1.0 / (2.0 * T), N // 2)
plt.figure()
plt.plot(xf, 2.0 / N * np.abs(yf[0:N // 2]))
plt.figure()
plt.plot(x, y)
plt.grid()

plt.show()