Christian Hennig wrote:
Hi,

is it true that the only way to tell rpart which variables to use
is to specify every single variable in the formula and separate them with
"+"?

I wonder if this error...


rotree <- rpart(powerdata[,1]~powerdata[,2:3],
+ method="class")
Error in model.frame(formula, rownames, variables, varnames, extras,
extranames, : invalid variable type


...can be prevented by other means than...


rotree <- rpart(segments~V1.3+V1.9,

+ method="class",data=powerdata)


This works.
(The variables here are powerdata[,1] and [,2:3].)

But I do not want to write 200 variable names down, as this is the real
size of "powerdata".

Is there any way around that?

Christian

Consider to use


rotree <- rpart(segments ~ ., method = "class", data = powerdata)

The "." defines all variables in powerdata, except for "segments", as usual for formulas.

Uwe Ligges







***********************************************************************
Christian Hennig
Fachbereich Mathematik-SPST/ZMS, Universitaet Hamburg
[EMAIL PROTECTED], http://www.math.uni-hamburg.de/home/hennig/
#######################################################################
ich empfehle www.boag-online.de

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