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#!/usr/bin/env python
# -*- coding: utf-8 -*-
import numpy as np
import matplotlib.pyplot as plt
import pywt
import pywt.data
ecg = pywt.data.ecg()
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.smooth
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()
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