[R] SVM unbalanced classes

[Christian Schulz]

Hi,

SVM have got the option class.weights to put the 
apriori-distribution for your target variable.

To oversample, or undersample a specific class
you have imho write a own function!?

Perhaps it helps ,christian

 

Am Dienstag, 9. März 2004 11:29 schrieb 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