Re: [R] help with RandomForest classwt option

From: Betty Health <betty.health_at_gmail.com>
Date: Mon 29 Jan 2007 - 23:41:08 GMT

Thank you very much, Weiwei and Jim!

Yeah, I did read the post by Andy, the contributor of this package. It seems that classwt is not implemented yet. For Weiwei's options, I have a few more questions. Thanks!

"1. try to use rf in fortran by following the linky below http://www.stat.berkeley.edu/~breiman/RandomForests/cc_software.htm"

I read the Fortran code briefly. But I did not find the options for down sampling. So does that mean I need to do down sampling myself? Could you explain a little more about "2. make a wrapper function to do the down sampling by yourself"? You mean I can do it in R or in Fortran? Some links plz? I haven't done this before.

Yeah, cut off did change for the final classification results. However from what I tried, they did not influence how the nodes are split. So I would go further in the above 2 options.

Thank you again!

Betty

On 1/28/07, Weiwei Shi <helprhelp@gmail.com> wrote:
>
> Dear Betty:
>
> I could suggest 3 options:
>
> 1. try to use rf in fortran by following the linky below
> http://www.stat.berkeley.edu/~breiman/RandomForests/cc_software.htm
>
> 2. make a wrapper function to do the down sampling by yourself
>
> 3. try to use cutoff in randomForest, which might help in your situation.
>
> HTH,
>
> weiwei
>
> On 1/28/07, Betty Health <betty.health@gmail.com> wrote:
> > Hello there,
> >
> > I am working on an extremely unbalanced two class classification
> problems. I
> > wanna use "classwt" with "down sampling" together. By checking the
> rfNews()
> > in R, it looks that classwt is not working yet. Then I looked at the
> > software from Salford. I did not find the down sampling option. I am
> > wondering if you have any experience to deal with this problem. Do you
> know
> > any method or softwares can handle this problem?
> >
> > Thank you very much!!
> >
> > Betty
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@stat.math.ethz.ch 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.
> >
>
>
> --
> Weiwei Shi, Ph.D
> Research Scientist
> GeneGO, Inc.
>
> "Did you always know?"
> "No, I did not. But I believed..."
> ---Matrix III
>

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