Re: [R] multivariate splits

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Wed 21 Jun 2006 - 04:02:51 EST


From: Gavin Simpson
>
> On Tue, 2006-06-20 at 08:12 -0700, Scott Rollins wrote:
> > Glenn De'ath published a paper in 'Ecology' several years ago and
> > included S-Plus functions in the archives. I haven't looked at the
> > files, so I'm not sure what modifications would be necessary for R.
> >
> > De'ath, G. 2002. Multivariate regression trees: a new technique for
> > modeling species--environment relationships. Ecology 83:1105-1117.
> >
> > Archives: http://www.esapubs.org/archive/ecol/E083/017/
> >
> > Scott
>
> Glenn's code is in package mvpart on CRAN.
>
> Not sure if the OP wanted this or not, but the multivariate
> nature of mvpart is in allowing multivariate responses,
> common in ecological data analysis. The fitting is still done
> using rpart (actually a modified version of rpart to allow
> for the multivariate response).
>
> Gavin

The OP's reply to my follow-up to Torsten's message seems to indicate that he has univariate response. He wants something that can split on linear combinations of predictors, as described in the CART book, I believe. What I thought he wanted was something that finds some optimal subset of predictors to split each node.

I am not aware of any open source implementations of tree algorithms that does linear combination splits, perhaps others know better. I suppose Torsten's double bagging (in the ipred package) sort of does that, but in an ensemble rather than a single tree.

Andy  

> >
> >
> > > Date: Mon, 19 Jun 2006 16:17:40 +0200
> > > From: " B?lint Cz?cz " <elatine@gmail.com>
> > > Subject: [R] multivariate splits
> > > To: r-help <r-help@stat.math.ethz.ch>
> > > Message-ID: <fab4bcf70606190717r45a2030dg@mail.gmail.com>
> > > Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> > >
> > > Dear R users!
> > >
> > > Does someone know about any algorithms / packages in R,
> that perform
> > > classification / regression / decision trees using multivariate
> > > splits?
> > >
> > > I have done some research, but I found nothing. Packages
> "tree" and
> > > "rpart" seem only to be able to do CART with univariate splits.
> > >
> > > Thank you for your help!
> > >
> > > B?lint
> > >
> > > --
> > > Cz?cz B?lint
> > > PhD hallgat?
> > > BCE KTK Talajtan ?s V?zgazd?lkod?s Tansz?k
> > > 1118 Budapest, Vill?nyi ?t 29-43.
> >
> >
> > ---------------------------------
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> >
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