# varUsed

0th

Percentile

##### Variables used in a random forest

Find out which predictor variables are actually used in the random forest.

Keywords
tree
##### Usage
varUsed(x, by.tree=FALSE, count=TRUE)
##### Arguments
x
An object of class randomForest.
by.tree
Should the list of variables used be broken down by trees in the forest?
count
Should the frequencies that variables appear in trees be returned?
##### Value

If count=TRUE and by.tree=FALSE, a integer vector containing frequencies that variables are used in the forest. If by.tree=TRUE, a matrix is returned, breaking down the counts by tree (each column corresponding to one tree and each row to a variable).If count=FALSE and by.tree=TRUE, a list of integer indices is returned giving the variables used in the trees, else if by.tree=FALSE, a vector of integer indices giving the variables used in the entire forest.

randomForest
library(randomForest) data(iris) set.seed(17) varUsed(randomForest(Species~., iris, ntree=100))