Re: [R] Question about rpart and regression trees

From: Paul Smith <phhs80_at_gmail.com>
Date: Tue 23 Jan 2007 - 11:13:28 GMT

On 1/23/07, Prof Brian Ripley <ripley@stats.ox.ac.uk> wrote:
> > I would like to use rpart to obtain a regression tree for a dataset
> > like the following:
> >
> > Y X1 X2 X3 X4
> > 5.500033 B A 3 2
> > 0.35625148 D B 6 5
> > 0.8062546 E C 4 3
> > 5.100014 C A 3 2
> > 5.7000422 A A 3 2
> > 0.76875436 C A 6 5
> > 1.0312537 D A 4 1
> >
> > Y is the objective variable. X1, X2, X3 and X4 can take, respectively,
> > the following values:
> >
> > X1: A,B,C,D,E
> > X2: A,B,C,D,E
> > X3: 3,4,5,6
> > X4. 1,2,3,4,5
> >
> > Should I convert X3 and X4 to factor before running rpart?
>
> If they really are factors, yes.
> If they are ordered factors, no.

Thanks, Prof. Ripley. Is it correct to adopt the same procedure in case of classification trees, i.e., in case the objective variable (Y) is categorical and X1, X2, X3 and X4 are as above?

Paul



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