[R] stack overflow and predict()

[Liaw, Andy]

Try something like this (suppose x is the matrix of predictors in the
training set, and xtest is the same for the test set):

my.rp <- rpart(y ~ x, ...)
test.pred <- predict(my.rp, newdata=data.frame(x=I(xtest)))

Make sure the name of the variable in the data frame given to newdata
matches the name of the variable in the original formula, in this case `x',
a matrix.

HTH,
Andy


> From: Ji Zhu [mailto:jizhu at umich.edu] 
> 
> Dear R users,
> 
> I'm trying to use rpart() to build a classification tree on a 
> big dataset. The number of samples is n=100 and the number of 
> variables is p=10000.
> 
> At first I stored all the data in a data.frame and got a 
> "stack overflow" error; then I changed the data into a matrix 
> and the problem disappeared. Now the trouble is when I try to 
> use the predict() function, since each newdata is a long list 
> with p=10000 elements, the predict() function doesn't 
> recognize it and simply returns the fitted values at the 
> training data (rather than the newdata).
> 
> Could anyone give me some suggestion on how to proceed?  Thank you.
> 
> Regards,
> 
> Ji
> 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Ji Zhu                          439 West Hall
> Assistant Professor             550 East University
> Department of Statistics        Ann Arbor, MI 48109
> University of Michigan          (734) 936-2577 (O)
> jizhu at umich.edu                 (734) 763-4676 (F)
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~