[R] Re-evaluating the tree in the random forest

Martin Lam tmlammail at yahoo.com
Thu Sep 8 19:50:30 CEST 2005

Dear mailinglist members,

I was wondering if there was a way to re-evaluate the
instances of a tree (in the forest) again after I have
manually changed a splitpoint (or split variable) of a
decision node. Here's an illustration:


forest.rf <- randomForest(formula = Species ~ ., data
= iris, do.trace = TRUE, ntree = 3, mtry = 2,
norm.votes = FALSE)

# I am going to change the splitpoint of the root node
of the first tree to 1
forest.rf$forest$xbestsplit[1,1] <- 1

Because I've changed the splitpoint, some instances in
the leafs are not supposed where they should be. Is
there a way to reappoint them to the correct leaf?

I was also wondering how I should interpret the output
of do.trace:

ntree      OOB      1      2      3
    1:   3.70%  0.00%  6.25%  5.88%
    2:   3.49%  0.00%  3.85%  7.14%
    3:   3.57%  0.00%  5.56%  5.26%

What's OOB and what does the percentages mean?

Thanks in advance,


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