[R] Plotting Discriminants from qda

[David Winsemius]

On Feb 20, 2013, at 2:42 PM, Melanie Zoelck wrote:

> Dear R Help Members,
> 
> I am aware how to plot the LD1 vs LD2 from a lda in R, using the code:
> 
> plot(baseline.systat.hat$x, col=baseline.systat.hat$class,pch=as.numeric(baseline.systat.hat$class))
> 
> However, I need to use the quadratic discriminant function, qda due to data properties. Is there a way to obtain the same sort of plot for from a qda object (and the output of predict qda). I have not been able to find this and am a bit stumped. I cannot seem to find any information on plotting this.
> 

Code for plotting qda results appears on p340 of MASSe4. However the comment that "Function predplot is given in the scripts" is not something I was able turn into anything useful after looking in hte index, searching the MASS website. Searching with Google for 'ripley MASS predplot' I find an R help posting by Gavin Simpson in 2003 that pointed to the file ch11.R in the MASS library, but I find that in the meantime it has moved to ch12.R in the "scripts" directory of ../library/MASS/

-- 

David Winsemius
Alameda, CA, USA