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

`varUsed(x, by.tree=FALSE, count=TRUE)`

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?

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.

# NOT RUN { data(iris) set.seed(17) varUsed(randomForest(Species~., iris, ntree=100)) # }