R help - May 2000 - Graph superimposition

I'm running a four-group, 15-variable discriminant analysis using the MASS 
function lda().  Discriminant functions 1 and 2 explain about 93% of the 
variance.  I would like to plot the group scatters in a single scatterplot, 
identify each group's centroid, and encircle the group scatter with a 90% 
bivariate confidence ellipse.  I can do this for each group on a separate 
plot, but I cannot figure out how to place all information on a single 
plot.   In S-Plus I use trellis graphics with panel.superpose as a trellis 
option.

I know that R does not support trellis graphics, but is there another way 
to accomplish this in R?  (I'm using 1.0.1 under Windows NT 4).

Thanks for your help.

P.S.  My needs stem from wanting to use "R" as the statistical
language for
a course I'm teaching next Fall.


====================Dr. Marc R. Feldesman
Professor and Chairman
Anthropology Department
Portland State University
1721 SW Broadway
Portland, Oregon 97201
email:  feldesmanm at pdx.edu
phone:  503-725-3081
fax:    503-725-3905
http://odin.cc.pdx.edu/~h1mf
=====================
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Marc Feldesman <feldesmanm at pdx.edu> writes:
> I'm running a four-group, 15-variable discriminant analysis using the
MASS
> function lda().  Discriminant functions 1 and 2 explain about 93% of the 
> variance.  I would like to plot the group scatters in a single scatterplot,
> identify each group's centroid, and encircle the group scatter with a
90%
> bivariate confidence ellipse.  I can do this for each group on a separate 
> plot, but I cannot figure out how to place all information on a single 
> plot.   In S-Plus I use trellis graphics with panel.superpose as a trellis 
> option.
> 
> I know that R does not support trellis graphics, but is there another way 
> to accomplish this in R?  (I'm using 1.0.1 under Windows NT 4).
Well, you can always superimpose plots by using the following paradigm

  plot(1:10)
  par(new=T)
  plot(1:10,cex=2)

There might be a simpler way using the features for adding items to
a plot (e.g. points(), lines()).

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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