[Pkg-exppsy-pymvpa] model selection and other questions

Yaroslav Halchenko debian at onerussian.com
Mon Apr 7 14:44:10 UTC 2008

On Mon, 07 Apr 2008, Emanuele Olivetti wrote:

> > Thanks for sharing the experience -- we should give them a spin too but
> > lots of changes should happen first to make that viable  -- for
> > instance, now considerable amount of 'training' of SVMs is taken by
> > transforming data into 'library' space.
> I don't get the point, but I'll catch it eventually, since I'm playing
> with pyMVPA now.
just look for convert2SVMNode in case of libsvm.
I believe that scikits.learn had it slightly more effective, but I might
be wrong

In case of shogun -- it is not only that: shogun precomputes kernels'
matrix, thus if datasamples didn't change, it is not needed to recompute
it if only parameters of SVM  (not of the kernel) has changed (ie C for
soft-margin C-SVM). 

> Bye,

> Emanuele

Yaroslav Halchenko
Research Assistant, Psychology Department, Rutgers-Newark
Student  Ph.D. @ CS Dept. NJIT
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