Le 16 mars 2012 15:29, Andreas Müller <[email protected]> a écrit : > On 03/16/2012 11:12 PM, James Bergstra wrote: >> I was also recently bit by this scale_C business. It looks like the >> decision to make scale_C=True the un-changeable default has already >> been made, but when this is done *PLEASE* make this abundantly clear >> in the documentation... my understanding was that the C in the SVM >> equation means the thing that Ian referred to, and which libSVM uses, >> and shogun, etc... rather than this "conveniently scaled" >> alternative. Maybe this new parameter should be renamed to something >> other than "C" so that SVC(C=foo) fails rather than computes a >> surprising thing? Anyway, I'm sure this is off-topic, but if someone >> could point me to a more appropriate discussion thread I'd appreciate >> it. > > > Hi James. > There was some discussion on this going on pretty invisible here: > https://github.com/scikit-learn/scikit-learn/commit/b3839837cf949db8e9122807578ebce6bf3d6fb4#commitcomment-1022876 > > Maybe we should open an issue on this? > Alex wanted to change the default behavior for "C". > I'm not sure if this will actually make everything ok again ;) > (Also I'm not sure if this was maybe already merged?) > > I have to say that I am also not entirely happy with this step > but changing the API _again_ would be ... well... pretty > unfortunate.
AFAIK the new "scale_C=true" by default has not been released yet. I agree, that using C for a scaled regularizer parameter is misleading for people who are familiar with the libsvm and liblinear convention. That's why I proposed to rename it use "alpha" instead of C to be consistent with the other regularized models of the project (and esp. linear models such as RidgeRegression, SGDClassifier, ElasticNet, LassoLars and friends). -- Olivier http://twitter.com/ogrisel - http://github.com/ogrisel ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Scikit-learn-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/scikit-learn-general
