[R] panel.levelplot() for 2D histograms

[Vermeiren, Hans [VRCBE]]

Dear R-wizards,
I'm trying to plot "binned scatterplots", or 2d histograms, if you wish, for
a number of groups by using the lattice functionality
it works fine for one group at a time, and probably I could find a
work-around, but I prefer to do it the elegant way
here's an example of what I want, what I tried and where it goes wrong:

require(gregmisc)
require(lattice)
#toy dataset:
ds<-data.frame(x=rnorm(3000),y=rnorm(3000),group=rep(factor(c("A","B","C")),
1000))

# this binscatter-function shows what I want,
# I just would like to have it as a panel function

binscatter<-function(x,y){
 col<-rev(gray.colors(5))
 breaks=c(1,5,10,100,500,100000)
 h2d<-hist2d(x=x,y=y,nbins=10,same.scale=T,show=F)
 image(h2d$x,h2d$y,h2d$counts,breaks=breaks,col=col,axes=T)
}


# for one group, this works fine
A<-subset(ds,group=="A")
binscatter(A$x,A$y)

# simple xyplot does too (of course)
xyplot(y~x|group,data=ds)

# but my lattice-ified version of binscatter does not:
# 1st attempt
panel.binscatter<-function(x,y,subscripts,...){
 col<-gray.colors(5)
 breaks=c(1,5,10,100,500,100000)
 h2d<-hist2d(x=x,y=y,nbins=10,same.scale=T,show=F)
 
panel.levelplot(h2d$x,h2d$y,h2d$counts,subscripts=1:length(h2d$x),at=breaks,
col.regions=col,region=T)
}

xyplot(y~x|group,data=ds,panel=panel.binscatter)

# but, this doesnt work either for one group using levelplot() :
Ah2d<-hist2d(A$x,A$y,nbins=10,same.scale=T,show=F)
levelplot(Ah2d$counts~Ah2d$x*Ah2d$y)

# but this DOES:
grid<-expand.grid(x=Ah2d$x,y=Ah2d$y)
levelplot(Ah2d$counts~grid$x*grid$y)

#2nd attempt doesn't work, I give up..
panel.binscatter<-function(x,y,subscripts,...){
col<-gray.colors(5)
breaks=c(1,5,10,100,500,100000)
h2d<-hist2d(x=x,y=y,nbins=10,same.scale=T,show=F)
grid<-expand.grid(x=h2d$x,y=h2d$y)
panel.levelplot(grid$x,grid$y,h2d$counts,subscripts=1:length(h2d$x),at=break
s,col.regions=col)
}

xyplot(y~x|group,data=ds,panel=panel.binscatter)

all suggestions welcome, thanks a lot

Hans