import numpy as np
import matplotlib.pyplot as plt

def stft(x, L, overlap, window):
    opoints = int(L*overlap)
    X = np.array([np.abs(np.fft.fft(window*x[i:i+L])[:L//2])
                 for i in range(0,len(x)-L,opoints)])
    return X

t = np.linspace(0, 5, 11025*5)

xf = np.linspace(0, 2000, 11025*5)
w = 2*np.pi*xf
x = np.sin(w*t)

f = np.linspace(0, 11025, 1024)

window = np.hanning(1024)

stft = stft(x,1024,0.5,window)

plt.imshow(stft[:1024//2].T, cmap = plt.get_cmap('gist_yarg'), origin='lower', aspect='auto',
                 interpolation='nearest', extent=(0,5, 0,11025/2))

plt.xlabel("Time [s]")
plt.ylabel("Frequency [Hz]")
plt.show()