[pymvpa] RFE + SplitClassifier

Michael Hanke mih at debian.org
Sun Jul 22 08:33:52 UTC 2012


On Fri, Jul 20, 2012 at 08:35:25AM +0200, mhampel at uni-osnabrueck.de wrote:
> I'm currently working on my master thesis and using the PyMVPA toolbox for
> the analysis of my fMRI data. My script for Recursive Feature Elimination
> (RFE) is working with a CrossValidation but unfortunately not with a
> SplitClassifier. Could you please give me some advice on that?
> In my script (see below) I use the RFE example from the documentation. If
> I add a CrossValidation I get an error value for each validation step. But
> I'm also interested in the sensitivity maps of each step and I couldn't
> figure out if that is possible with CrossValidation. Therefore, I tried to
> use a SplittClassifier but I always get the same error message in
> self.train(ds).
> Could someone tell me the difference between SplitClassifier and
> CrossValidation? I assumed that the SplitClassifier also does a
> cross-validation internally. What do I have to change in my code to make
> it work?

Your assumption is correct and your approach sounds appropriate. Could
you please provide some more information on your dataset (``print
ds.summary``) and the actual error message (incl. traceback) that you
are observing? At first glance, and without this additional information
I can't see an obvious problem.



Michael Hanke

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