[R] about randomForest

Liaw, Andy andy_liaw at merck.com
Wed Jan 7 15:50:41 CET 2009


Apologies for catching this so late.  Have been out for a few weeks and still trying to recover from that...

From: Jim Porzak
> 
> Hi Wanghong,
> 
> Unless you have a huge linux box, you will need to sample 
> down your 300k
> rows to a few thousand.
> 
> In marketing aps, I often have data sets of comparable size.
> 
> I would suggest you start with a just a few k rows to make 
> sure everything
> else is working as you wish. Also, study carefully Andy's 
> randomForest docs
> - including the R News article a couple years ago.
> 
> In particular,
> 
> 1) the formula interface is a memory hog. Andy suggests just 
> using explicit
> declaration. In you case, something like
>       randomForest(Memebers[42], Memebers[-42], ...

Actually that first argument probably should be Members[[42]].  I believe you get a data frame with one variable if you do Members[42].

Best,
Andy

> 2) proximity matirx is also memory & time intensive. Suggest 
> proximity =
> FALSE until, other things sorted out.
> 
> HTH,
> Jim Porzak
> TGN.com
> San Francisco, CA
> http://www.linkedin.com/in/jimporzak
> useR Group SF: http://ia.meetup.com/67/
> 
> 
> 2008/12/26 wanghong <wanghong at neusoft.edu.cn>
> 
> > hello,
> > I want to use randomForest to classify a matrix which is 
> 331030¡Á42,the last
> > column is class signal.I use £º
> > 
> Memebers.rf<-randomForest(class~.,data=Memebers,proximity=TRUE
> ,mtry=6,ntree=200)
> > which told me" the error is matrix(0,n,n) set too elements"
> > then I use:
> > 
> Memebers.rf<-randomForest(class~.,data=Memebers,importance=TRU
E,proximity=TRUE)
> > which told me"the error is na.fail.default(list(class = 
> c(17L, 17L, 17L,
> > 29L, 29L, 29L,  :
> >  missing values in object
> > "
> >
> > what's wrong with it .Thanks a lot
> >
> >
> > wanghong
> >  wanghong at neusoft.edu.cn
> > 2008-12-26
> > ______________________________________________
> > R-help at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> > http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
> 
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> 
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