R help - Feb 2003 - interpolation and 3D plots

I've been told that you may be able to help.

I have a complex linear model with multiple two-way interaction terms. Is
there a way to view the interaction terms in a 3d plot equivalent to the S
functions:
 
> plan<-interp(x,y,z)
> image(plan)
where x and y are my explanatory variables and z my response variable.

Thanks,

Jonatha Davies

library(akima)
plan <- interp.old(x,y.z)
image(plan)

is very close.

This is in MASS (the book) with examples.

On Mon, 3 Feb 2003, Davies, Jonathan wrote:
> I've been told that you may be able to help.
> 
> I have a complex linear model with multiple two-way interaction terms. Is
> there a way to view the interaction terms in a 3d plot equivalent to the S
> functions:
>  
> > plan<-interp(x,y,z)
> > image(plan)
> 
> where x and y are my explanatory variables and z my response variable.
-- 
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

Dear Jonathan,

The all.effects function in the car package will identify the high-order 
terms in a linear or generalized-linear model and absorb terms marginal to 
them (e.g., for a two-way interaction, the main effects marginal to the 
interaction and the constant). The plot method for the object produced uses 
trellis graphics to plot terms, but for a two-way interaction, the 
information in the object could easily be plotted as an image (or other 3D) 
plot.

I hope that this helps,
  John

At 10:02 AM 2/3/2003 +0000, Davies, Jonathan wrote:
>I've been told that you may be able to help.
>
>I have a complex linear model with multiple two-way interaction terms. Is
>there a way to view the interaction terms in a 3d plot equivalent to the S
>functions:
>
> > plan<-interp(x,y,z)
> > image(plan)
>
>where x and y are my explanatory variables and z my response variable.
-----------------------------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada L8S 4M4
email: jfox at mcmaster.ca
phone: 905-525-9140x23604
web: www.socsci.mcmaster.ca/jfox
-----------------------------------------------------