[R] erro in SVM (packsge "e1071")

[João Mendes Moreira]

The way I call SVM is:

i <- (-2)
j <- 4
learner='svm'
learner.pars=list(Duracao ~ ., data=orig.data,
   scale=c(FALSE, TRUE, TRUE, FALSE, FALSE, FALSE, TRUE,
    FALSE, FALSE, FALSE, FALSE, FALSE, FALSE,
    FALSE, FALSE, FALSE),
   type='nu-regression', kernel='linear',
   cost=2^(2*i), nu=j/10)
learner.pars$data <- orig.data[begin.test.pos:(test.pos-1),]

model <- do.call(learner,learner.pars)

The variables begin.test.pos and test.pos are windexes for orig.data and are 
working well. in this case begin.test.pos = 1 and test.pos = 875.

orig.data is a data.frame where the second, third and seventh parameters are 
numeric. The first parameter  is a date and all the others are factors (some 
of them ordered). The ordered factors are: Dia Semana (week day), DiaAno 
(day of the year), DiaMes (day of the month), SemanaAno (week of the year) 
and SemanaMes (week of the month).
The first two lines of the orig.data data.frame are:
         Data       InicioViagem Duracao     DiaSemana  TipoDia EpocaEscolar 
DiasDesdeUltPagamento DiaAno DiaMes FluxoEntrada FluxoSaida
13 2004-01-01        25056    3220        quinta-feira   feriado 
normal                     9                        1             1 
normal           fsp4
9  2004-01-01        28554    2866         quinta-feira   feriado 
normal                     9                        1             1 
normal           fsp4
            Modelo                  Motorista SemanaAno SemanaMes Servico
13    Mercedes_O530_N     10701         1             1 
10597
9      Mercedes_O530_N     11292         1             1 
10597

I am using sliding window with 30 days (around 900 records) for training.
The error is in the svm function. May be because SVM uses other functions, 
but it happens when I run svm.

Thanks a lot for the help

Joao
_______________________________________________
FEUP - Engineering Faculty, Porto University
Engineering and Industrial Management group
Tel.: +351 22 508 1639
Fax: +351 22 508 1538

----- Original Message ----- 
From: "David Meyer" <david.meyer at wu-wien.ac.at>
To: <jmoreira at fe.up.pt>
Cc: <r-help at stat.math.ethz.ch>
Sent: Sunday, December 19, 2004 1:23 PM
Subject: Re: [R] erro in SVM (packsge "e1071")


> Joao:
>
> The reported error message is not from e1071.
> How *exactly* did you call svm()?
>
> As to the documentation of the nu parameter: yes, this is an omission,
> of course, nu is used in nu-regression as well; thanks for pointing this
> out.
>
> best,
> David
>
> ---------
>
> Hello,
>
> I am using SVM under e1071 package for nu-regression with 18 parameters.
> The
> variables are ordered factors, factors, date or numeric datatypes. I use
> the
> linear kernel.
> It gives the following error that I cannot solve. I tryed debug, browser
> and
> all that stuff, but no way.
> The error is:
>
> Error in get(ctr, mode = "function", envir = parent.frame())(levels(x),
> :
>        Orthogonal polynomials cannot be represented accurately enough
> for 236
> degrees of freedom
>
> I use the nu parameter. However, reading ?svm help it says "parameter
> needed
> for 'nu-classification' and 'one-classification'". Does not say anything
> about
> nu-regression. It is an omission in the ?svm help page? Or am I
> notundestanding something?
>
> I believe it has something to do with the calculus of the eigenvalues.
> Anyway
> how can I overpass this problem? Increasing the training data (is around
> 900
> records)?
>
> Thanks for any help
>
> Joao
>
>
>
>
> -- 
> Dr. David Meyer
> Department of Information Systems
>
> 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/
>