[R] Question about rpart and regression trees

[Paul Smith]

On 1/23/07, Prof Brian Ripley <ripley at 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