[R] SVM unbalanced classes

[Frank Gerrit Zoellner]

Hi!

I am using R 1.8.1 and the svm of the e1071 package for classification.
The problem is that I have unbalanced classes e.g. the first one is much bigger than the second one and therfore the svm is biased to the first class.
If I manually adjust the class size the bias disappears.
The question is then how to include this unequal class distribution to the svm (e.g. via wheights or costs)?

Yours,
Frank
-- 
Frank G. Zoellner
AG Angewandte Informatik
Technische Fakult"at
Universit"at Bielefeld
phone: +49(0)521-106-2951
fax:   +49(0)521-106-2992
email: fzoellne at techfak.uni-bielefeld.de