Greetings! With the help of Pauli, I've created a git clone of the scipy tree and made a cwt branch. The branch is located at http://github.com/lesserwhirls/scipy-cwt/tree/cwt Here is an example using the cwt code with the Mexican Hat wavelet: ============== import numpy as np from scipy.signal import SDG, Morlet, cwt # create data array - number of tropical cyclones per year (1970-2006) in the # Northwest Australian region data = np.array([5,6,8,8,11,6,4,4,2,6,7,9,4,8,10,8,4,14,5,5,2,2,7,3,7,5,5,7,9,5,3,6,5,5,7]) # remove mean data = (data - data.mean()) # create the scales at which you wish to do the analysis scales = np.arange(1,15,0.1) # initialize the mother wavelet mother_wavelet = SDG(len_signal = len(data), pad_to = np.power(2,10), scales = scales) # perform continuous wavelet transform on `data` using `mother_wavelet` wavelet=cwt(data, mother_wavelet) # plot scalogram, wavelet power spectrum, and time series wavelet.scalogram(ts = data, show_coi = True, show_wps = True, use_period = True, ylog_base = 2) ============== I'll add an enhancement ticket in Scipy's Trac once I get some initial feedback. Cheers! Sean Arms Graduate Research Assistant School of Meteorology University of Oklahoma On Mon, Mar 2, 2009 at 10:25 PM, Sean Arms <lesserwhirls@gmail.com> wrote:
Greetings!
My name is Sean Arms and I'm a graduate student at the University of Oklahoma in the School of Meteorology. As part of my PhD research, I'm studying coherent structures in atmospheric boundary layer turbulence, primarily using in-situ observations and, secondarily, Direct Numerical Simulation (DNS) output. One common approach for detecting coherent structures in observational datasets relies on the use of the global wavelet power spectrum as estimated from a continuous wavelet transform (CWT). I know SciPy has a DWT impementation, and I've already been in contact with Filip. He recommeded that I post my code in hopes that it would add some momentum to the python-cwt development and create some feedback (I'm currently looking for a good place to post my code). I've implemented the CWT using pure python (that is, I did not write any C extension code myself - nothing to build), along with one mother wavelet (second derivitive of a Gaussian, or the Mexican Hat) - I'll be adding more Mother wavelets as I go along. I've made it a point to (try to) design my MotherWavelet class to be easily extendable. I'm working on documentation and a few tests at the moment, but so far my code compares well with other wavelet routines.
The point of this email is to introduce myself and let the SciPy dev community know that I am willing to help develop CWT support for SciPy - I'll already be doing the work for my research, so I might as well put in the extra effort to make is usable by the larger community!
Cheers!
Sean Arms Graduate Research Assistant School of Meteorology University of Oklahoma