gistfile1.py

%matplotlib inline
import matplotlib.pyplot as plt
import numpy as np
import scipy.fftpack

SAMPLE_RATE = 12800
FFT_SIZE = 32768



def plot_spectrum(y, title):
    plt.figure(figsize=(19,4))
    plt.title(title)
    plt.grid(True)
    bin_width = 1.0*SAMPLE_RATE/FFT_SIZE
    x_vals = np.array(np.linspace(0.0, len(y), num=len(y))*bin_width)
    #print "len_x = %d, len_y = %d" % (len(x_vals), len(y))
    plt.plot(x_vals, np.log10(np.array(y)/len(y)), c="b")
    return True


def plot_time(y, title):
    plt.figure(figsize=(19,4))
    plt.title(title)
    plt.plot(y, c="g")
    return True

def fft(x):
    window = np.hamming(FFT_SIZE)
    return np.abs(window*scipy.fftpack.fft(x))


data = np.loadtxt("/Users/ati/Downloads/ua.txt", dtype=np.float)

#plot_time(data[0:2048], "src")
plot_spectrum(fft(data[0:FFT_SIZE])[0:FFT_SIZE/4], "fft_size = %d"%FFT_SIZE)
plot_spectrum(fft(data[0:FFT_SIZE])[0:FFT_SIZE/16], "fft_size = %d"%FFT_SIZE)