Wavelet plot with Python libraries

python matplotlib scipy wavelet pywt
hyperboreean picture hyperboreean · Jul 7, 2009 · Viewed 10.8k times · Source

I know that SciPy has some signal processing tools for wavelets in scipy.signal.wavelets and a chart can be drawn using Matplotlib, but it seems I can't get it right. I have tried plotting a Daubechies wavelet against a linear space, but it's not what I am looking for. I am highly unskilled about wavelets and math in general . :)

Answer

nigma picture nigma · Jul 13, 2009

With a recent trunk version of PyWavelets, getting approximations of scaling function and wavelet function on x-grid is pretty straightforward:

[phi, psi, x] = pywt.Wavelet('db2').wavefun(level=4)

Note that x-grid output is not available in v0.1.6, so if you need that you will have to use the trunk version.

Having that data, you can plot it using your favourite plotting package, for example:

import pylab
pylab.plot(x, psi)
pylab.show()

A very similar method is used on wavelets.pybytes.com demo page, but there the charts are done with Google Charts for online presentation.

Related questions

What does .shape[] do in "for i in range(Y.shape[0])"?

I'm trying to break down a program line by line. Y is a matrix of data but I can't find any concrete data on what .shape[0] does exactly. for i in range(Y.shape[0]): if Y[i] == -1: This program …

Read More
A tool to convert MATLAB code to Python

I have a bunch of MATLAB code from my MS thesis which I now want to convert to Python (using numpy/scipy and matplotlib) and distribute as open-source. I know the similarity between MATLAB and Python scientific libraries, and converting …

Read More
MatPlotLib: Multiple datasets on the same scatter plot

I want to plot multiple data sets on the same scatter plot: cases = scatter(x[:4], y[:4], s=10, c='b', marker="s") controls = scatter(x[4:], y[4:], s=10, c='r', marker="o") show() The above only shows the most recent scatter() I've …

Read More