getting probabilities from SVM

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

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/