Thanks for the background.  I wasn't being critical.  You actually forced me
to learn something new as I hand't used attributes before.  That's why it
took me a while to figure it out.

Thanks,

Roger


On 2/17/06, David Meyer <david.meyer@wu-wien.ac.at> wrote:
>
> > Finally figured it out.  You have to extract it from the attributes.
> > Tricky.  Thanks anyway.
>
> > attr(pred, "prob")[1:10,]
>
> Correct.
>
> Just for the records, the rationale behind this `tricky' design:
>
> In addition to probabilites, predict.svm() (more precisely: libsvm) can
> also compute the decision values. Common ways to handle `polymorph'
> prediction types are, e.g, using a `type' argument in the predict()
> function, or to return all variants in one list object. With a `type'
> argument, you need several calls to predict() if you need, say, hard
> predictions _and_ the probabilities. On the other hand, the probability and
> decision values features were added to libsvm only when svm() in e1071 had
> already been around for a while, so returning a list instead of a vector
> would have broken a lot of code. So I decided to keep the `standard' predict
> behavior and to `hide' special predictions in an attribute. If the latter
> had been available from the beginning, I probably would have used the `type'
> approach.
>
> Cheers,
> David
>
>
> On 2/16/06, roger bos <roger.bos@gmail.com> wrote:
> >
> > I am using SVM to classify categorical data and I would like the
> > probabilities instead of the classification.  ?predict.svm says that its
> > only enabled when you train the model with it enabled, so I did that,
> but it
> > didn't work.  I can't even get it to work with iris.  The help file
> shows
> > that probability = TRUE when training the model, but doesn't show an
> > example.  Then I try to predict with probabilities, I still only get
> > classifications back.  Anyone get this to work and can help me out?
>
> --
> Dr. David Meyer
> Department of Information Systems and Operations
>
> Vienna University of Economics and Business Administration
> Augasse 2-6, A-1090 Wien, Austria, Europe
> Fax: +43-1-313 36x746
> Tel: +43-1-313 36x4393
> HP:  http://wi.wu-wien.ac.at/~meyer/
>

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