[R] order panels in xyplot by increasing slope

[Jim Lemon]

On 05/24/2013 06:21 AM, Belair, Ethan D wrote:
> example.plot = xyplot(ht ~ time|tree, data=data,
>                  type = c("r", "g", "p"),
>                  par.settings=simpleTheme(col="blue"),
>               main="abc",
>               )
> example.plot
 > ...

Hi Ethan,
This may be what you want:

panel.slope<-function(panel) {
  return(diff(range(panel$y,na.rm=TRUE))/
   diff(range(panel$x,na.rm=TRUE)))
}
panel.order<-
  order(unlist(lapply(example.plot$panel.args,panel.slope)))

Jim