Re: [Rd] Classification Trees and basic Random Forest pkg using t ree structures in C

From: Liaw, Andy <andy_liaw_at_merck.com>
Date: Fri 04 Nov 2005 - 19:00:03 GMT


> From: Hin-Tak Leung
>
> Izmirlian, Grant (NIH/NCI) wrote:
> <snipped>
> > The only interesting feature is that the tree structure has been
> > implemented in C. Its a neater way to carry stuff around and I am
> > guessing would make future implementation easier.
> >
> > Because of its inherent redundancy from the users standpoint, it
> > isn't something to send to CRAN. However, I was wondering whether
> > anyone is interested in a copy?
>
> Hi,
>
> Hmm, why didn't you just post a URL?

Isn't it a bit too much to assume that everyone has a personal web space somewhere?

> Incidentally I am actually very
> interested in seeing your code. I am working on a project where
> the data set is extremely large, but the permuntation of the states of
> the data is extremely small. Each piece of data consists of only 4
> states, so stuffing it as an R object (which takes up 32-byte? on
> 32-bit machines) or even an char vector is quite wasteful; so I
> have written a "strange" data.frame where internally it uses only
> 2-bit for storage. (it is still work-in-process but I have got to
> the point of being able to get and set each 2-bit cell now).

For some of the data we encounter, all X variables are binary, so each data point can be encoded into a bitstring. There are algorithms that take advantage of that. The problem is interfacing such code with R. I know of no good solutions. As I told Grant, I thought about what he did, too, but the difficulty is how to pass such data structures to R. Actually, some time down the road I might try to use the dendrogram class that's in R, and manipulate them in C. Not sure about efficiency though.

Andy  

> Hin-Tak Leung
>
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
>



R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel Received on Sat Nov 05 06:04:40 2005

This archive was generated by hypermail 2.1.8 : Mon 20 Feb 2006 - 03:21:33 GMT