From: Dror > > Hi, > I need help with the randomForest prediction. i run the folowing code: > > > iris.rf <- randomForest(Species ~ ., data=iris, > > importance=TRUE,keep.forest=TRUE, proximity=TRUE) > > pr<-predict(iris.rf,iris,predict.all=T) > > iris.rf$votes[53,] > setosa versicolor virginica > 0.0000000 0.8074866 0.1925134 > > table(pr$individual[53,])/500 > > versicolor virginica > 0.928 0.072 > > > > why the voting is not the same for the same data? what do i do wrong?
It's because the $votes components reflects the OOB predictions, whereas predict() gives you predictions based on all of the trees in the forest. > another 2 questions: > 1. i tries to debug another problem in which the individual vector was > smaller the tree number in the forest. > i noticed that in this row of code: > > treepred <- matrix(object$classes[t1$treepred], nrow = > length(keep), > dimnames = list(rn[keep], NULL)) > the t1$treepred has values of 0 (i have 2 classes) and they > droped from the > results > what does this 0 mean? Not sure why you're debugging that portion of the code. That is just to dimension the array passed back from C into a matrix. What is "t1"? > 2. how can i drop a tree from the forest? Look at the $forest component of the randomForest object, and subset the dimension that correspond to ntree in all of its components. Change $ntree accordingly. Andy > Thanks, > Dror > -- > View this message in context: > http://n4.nabble.com/Random-Forest-prediction-questions-tp1573 > 530p1573530.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > Notice: This e-mail message, together with any attachme...{{dropped:10}} ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
