[R] How to draw the decision boundaries for LDA and Rpart object

[Prof Brian Ripley]

On Wed, 9 Aug 2006, Am Stat wrote:

> Dr. Ripley,

R-help is not the address of `Dr. Ripley', nor even that of the person who 
wrote to you.

> Thanks very much for your help. I have used your partition tree and it works 
> well.  I am not familiar with the 'tree' package but I found that the 
> threshold to make a cut  returned by tree and rpart is almost the same 
> value.
> 
> Does that mean the decision boundaries for Rpart and Tree are the same for a 
> same data when using the default  value of parameters, no matter what the 
> structure of data  is?

No, they can differ.  There are comparisons in MASS (the book).

> 
> Thanks very much!
> 
> Leon
> 
> 
> 
> 
> ----- Original Message ----- 
> From: "Prof Brian Ripley" <ripley at stats.ox.ac.uk>
> To: "Am Stat" <amstat2006 at gmail.com>
> Cc: <r-help at stat.math.ethz.ch>
> Sent: Wednesday, August 09, 2006 3:04 AM
> Subject: Re: [R] How to draw the decision boundaries for LDA and Rpart 
> object
> 
> 
> > On Wed, 9 Aug 2006, Am Stat wrote:
> >
> >> Hello useR,
> >>
> >> Could you please tell me how to draw the decision boundaries in a
> >> scatterplot of the original data for a LDA or Rpart object.
> >
> > There are examples in MASS (the book).
> >
> >> For example:
> >> > library(rpart)
> >> >fit.rpart <- rpart(as.factor(group.id)~., data=data.frame(Data) )
> >>
> >>
> >> How can I draw the cutting lines on the orignial Data?
> >>
> >> Or is there any built in functions that can read the rpart object
> >> 'fit.rpart' to do that?
> >
> > See partition.tree in package tree.
> >
> >> PLEASE do read the posting guide 
> >> http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >
> > -- 
> > 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 272866 (PA)
> > Oxford OX1 3TG, UK                Fax:  +44 1865 272595
> 
> ______________________________________________
> R-help at 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.
> 

-- 
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 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595