[R] svm and scaling input

[Uwe Ligges]

Arne.Muller at sanofi-aventis.com wrote:
> Dear All,
> 
> I've a question about scaling the input variables for an analysis with svm (package e1071). Most of my variables are factors with 4 to 6 levels but there are also some numeric variables.
> 
> I'm not familiar with the math behind svms, so my assumtions maybe completely wrong ... or obvious. Will the svm automatically expand the factors into a binary matrix? If I add numeric variables outside the range of 0 to 1 do I have to scale them to have 0 to 1 range?


Well, this depends on the kernel in use.
For radial basis functions (as an example), you do not have to rescale, 
but a transformation of variables might make sense in order to get 
better results, though.

Uwe Ligges


> 
> thanks a lot for help,
> 
> 	+kind regards,
> 
> 	Arne
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html