[R] interpolation and 3D plots

[John Fox]

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
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