Multi-peak fitting: how to extract results

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Tue, 03/06/2012 - 03:34 pm

I would like to extract some results from the Multi-peak Fitting version 2. Specifically, I want to export the peak center and the error in the peak center to some waves of my choice, in a fashion analogous to WaveStats' V_avg and V_sdev. Unfortunately, I am not seeing a good way of doing this besides manually typing in values into a wave.

What I would really like to do is import a wave and then have MPF fit two peaks in the wave (always will be Lorentzian and without fail in the same general regions of the wave) and spit this same data (peak center and sdev in the peak center) into a results wave. But I am having trouble seeing how to do this quickly and efficiently using either MPF2_DoMPFit() or MPF2_AutoMPFit().

Any suggestions?
Additionally, I know that all this data is generated and stored in subfolders off of root. Unfortunately, there is little documentation about what each of the objects in the subfolders is, making it nearly impossible to determine what is what. Again, any suggestions? I would love to automate what I am trying to do, but right now it is seeming infinitely more cost-efficient to do everything manually (MPFv2 my peaks to get the centers and sdev's of the centers, then type them in by hand into my desired waves).

March 6, 2012 at 04:44 pm - Permalink

Indeed, data extraction for export and subsequent use is a weak point of MPF2. And the contents of the data folders are purposely not documented, so that I can change it in the future if I want. I consider all those waves and such to be an implementation detail subject to change.

Have said that, the coefficient waves are suggestively named "Peak N Coefs" where N is the peak number. This is unlikely to change, but I won't promise that it won't change.

If you're willing to write your own code that calls MPF2_DoMPFit(), then you control the list of coefficient waves, and you have direct access to them after the fit is done. As part of setting up the function, you create the list of coefficient waves (and the waves for that matter) and so you can access them after, extracting whatever info you want.

Note that the "derived" data like FWHM and such is not provided. You need to compute that after the fact.

John Weeks
WaveMetrics, Inc.
support@wavemetrics.com

March 7, 2012 at 10:19 am - Permalink