PyWavelets is a free Open Source library for wavelet transforms in Python.
Wavelets are mathematical basis functions that are localized in both time and
frequency. Wavelet transforms are time-frequency transforms employing wavelets.
They are similar to Fourier transforms, the difference being that Fourier
transforms are localized only in frequency instead of in time and frequency.

WWW: https://github.com/PyWavelets/pywt