[R] randomForests predict problem

[Yves Brostaux]

Hello everybody,

I'm testing the randomForest package in order to do some simulations and I 
get some trouble with the prediction of new values. The random forest 
computation is fine but each time I try to predict values with the newly 
created object, I get an error message. I thought I was because NA values 
in the dataframe, but I cleaned them and still got the same error. What am 
I doing wrong ?

 > library(mlbench)
 > library(randomForest)
 > data(Soybean)
 > test <- sample(1:683, 150, replace=F)
 > sb.rf <- randomForest(Class~., data=Soybean[-test,])
 > sb.rf.pred <- predict(sb.rf, Soybean[test,])
Error in matrix(t1$countts, nr = nclass, nc = ntest) :
         No data to replace in matrix(...)

I did it the same way with rpart and all worked fine :
 > library(rpart)
 > sb.rp <- rpart(Class~., data=Soybean[-test,])
 > sb.rp.pred <- predict(sb.rp, Soybean[test,], type="class")

Thank you all for any advice you can give to me.

-- 
Ir. Yves Brostaux - Statistics and Computer Science Dpt.
Gembloux Agricultural University
8, avenue de la Faculté B-5030 Gembloux (Belgium)
Tél : +32 (0)81 62 24 69
E-mail : brostaux.y at fsagx.ac.be
Web : http://www.fsagx.ac.be/si/