[R] Question about rpart and regression trees

[Prof Brian Ripley]

On Mon, 22 Jan 2007, Paul Smith wrote:

> Dear All
>
> 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.


-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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