content: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  import os
  
  import numpy as np
  import matplotlib.pyplot as plt
  
  import pywt
  
  
  ecg = np.load(os.path.join('data', 'ecg.npy'))
  
  data1 = np.concatenate((np.arange(1, 400),
                          np.arange(398, 600),
                          np.arange(601, 1024)))
  x = np.linspace(0.082, 2.128, num=1024)[::-1]
  data2 = np.sin(40 * np.log(x)) * np.sign((np.log(x)))
  
  mode = pywt.MODES.sp1
  
  
  def plot_signal_decomp(data, w, title):
      """Decompose and plot a signal S.
  
      S = An + Dn + Dn-1 + ... + D1
      """
      w = pywt.Wavelet(w)
      a = data
      ca = []
      cd = []
      for i in range(5):
          (a, d) = pywt.dwt(a, w, mode)
          ca.append(a)
          cd.append(d)
  
      rec_a = []
      rec_d = []
  
      for i, coeff in enumerate(ca):
          coeff_list = [coeff, None] + [None] * i
          rec_a.append(pywt.waverec(coeff_list, w))
  
      for i, coeff in enumerate(cd):
          coeff_list = [None, coeff] + [None] * i
          rec_d.append(pywt.waverec(coeff_list, w))
  
      fig = plt.figure()
      ax_main = fig.add_subplot(len(rec_a) + 1, 1, 1)
      ax_main.set_title(title)
      ax_main.plot(data)
      ax_main.set_xlim(0, len(data) - 1)
  
      for i, y in enumerate(rec_a):
          ax = fig.add_subplot(len(rec_a) + 1, 2, 3 + i * 2)
          ax.plot(y, 'r')
          ax.set_xlim(0, len(y) - 1)
          ax.set_ylabel("A%d" % (i + 1))
  
      for i, y in enumerate(rec_d):
          ax = fig.add_subplot(len(rec_d) + 1, 2, 4 + i * 2)
          ax.plot(y, 'g')
          ax.set_xlim(0, len(y) - 1)
          ax.set_ylabel("D%d" % (i + 1))
  
  
  plot_signal_decomp(data1, 'coif5', "DWT: Signal irregularity")
  plot_signal_decomp(data2, 'sym5', "DWT: Frequency and phase change - Symmlets5")
  plot_signal_decomp(ecg, 'sym5', "DWT: Ecg sample - Symmlets5")
  
  
  plt.show()
  