Sorry to answer to myself. A solution was trivial with lattice... (as often !)
library(lattice) modbusetmp<-lm(IKA_buse ~ Ct *Cc,data=dtbuse) G1<-cloud(IKA_buse~Ct*Cc,type="h",data=dtbuse) G2<-cloud(IKA_buse~Ct*Cc,data=dtbuse) seqCc<-seq(min(dtbuse$Cc),max(dtbuse$Cc),l=20) seqCt<-seq(min(dtbuse$Ct),max(dtbuse$Ct),l=20) grille<-expand.grid(Cc=seqCc,Ct=seqCt) zbuse<-predict(modbusetmp,newdata=grille,type=response) G3<-wireframe(zbuse~grille$Ct*grille$Cc) print(G3,more=T) print(G1,more=T) print(G2) Some obvious improvements can be done with labels and differencial colors (above or below the surface) can be attributed comparing observations to predicted values at the same x y values... Patrick Giraudoux a écrit : > Dear Listers, > > I would be interested in representing a trend surface including an > interaction term z = f(x,y,x.y) - eg the type of chart obtained with > persp() or wireframe(), then adding datapoints as a cloud, ideally > with dots which are under the surface in a color, and those who are > above in another color. An other option would be to draw segments > between the dots and the ground of the chart. > > scatterplot3d looks like being close to do such things except it does > not to include (to my knowledge) a coefficient for the interaction > term (thus just model z = f(x,y). > > Does anybody has an idea where to start with this and the main steps? > Or a place/website where some script examples can be found? > > Patrick > > ______________________________________________ R-help@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.