[R] predict.tree

ripley@stats.ox.ac.uk ripley at stats.ox.ac.uk
Tue May 21 13:04:08 CEST 2002


On Tue, 21 May 2002, poul svante wrote:

> I have a problem with interpretating the result of predict.tree,
> when I include the option split=T.
> E.g. running the example of the help file and concluding with
> >   predict(shuttle.tr, shuttle1,split=T)
> produces the output
>                      auto            noauto
> [1,] 0.015625002 0.007812502
> [2,] 0.007812502 0.000000000
> [3,] 0.000000000 0.000000000
> which is hard to interpret as a posterior probability.
> And since no values are missing for the predictors, I would
> expect to get the same result as with split=F?
>
> Comments?

It works correctly in S. Inside predict.tree you will find a function
pred2.tree, and inside that is a .C call.  Change double() to single().

We do recommend that you use rpart for tree construction, and by no means
all the options of package tree have been tested under R.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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