[R] Adding different output to different lattice panels

[deepayan.sarkar at gmail.com]

On 6/28/07, alxsal at free.fr <alxsal at free.fr> wrote:
> I would like to add a reference line to lattice graphs, with the reference
> line
> being different according to the factor level.
>
> Example : Draw 3 dotplots for "a","b" and "c" factors, and then add an
> horizontal line at y=10 for panel "a", y=8 for panel "b" and y=6 for panel
> "4"
>
> I tried the code below, but this draw all three reference lines for each
> panel.
> How do I index the current panel to chose the right reference vector value ?
>
> dat<-data.frame(id=rep(c("a","b","c"),4),val=1:12,quand=rep(c("t1","t2","t3","t4"),each=3))
> ref<-c(10,8,6)
> plot.new()
> datplot<-dotplot(val~quand|id,data=dat,panel=function(...){
> panel.dotplot(...)
> panel.abline(h=ref)
> })
> print(datplot)

dotplot(val~quand|id,data=dat,panel=function(...){
    panel.dotplot(...)
    panel.abline(h = ref[packet.number()])
})

(Things are more complicated if you have more than one conditioning variable.)

-Deepayan