[R] Question about panel.points

[Richard.Cotton at hsl.gov.uk]

> I'm trying to plot graphs using lattice with this script :
> 
> xyplot(Y ~ X | factmod,
> panel = function(x, y) {
>                 panel.grid(h=-1, v=-1, col="gray")
>                 panel.xyplot(x, y, type="p", pch=20)
>                 panel.points(50,Idata, data=devdata, col="red")   ----->
> this doesn't work
>                 },
>                  xlab="X", ylab="Y")
> 
> factmod is a factor with 18 labels corresponding to the 18 names of my
> devices.
> devdata is a data.frame of 2 columns and 18 rows : name of the devices /
> value of Idata for each device
> For example (smaller one):
> devdata<-data.frame(c("a","b","c","d"), c(1,5,9,7))
> 
> And I would like to add the point (50, Idata) per graph that is 
> points(50,1) on the first graph
> points(50,5) on the second graph, ...
> 
> At the moment, it plots all the points on every graph (or with another
> command, only (50,Idata[1]) on all the graphs).

You can use panel.number() or packet.number to specify code specific to 
different panels, e.g.

extrapoints <- seq(25,50,5)
panelfn <- function(...)
{
   panel.xyplot(...)
   panel.points(1, extrapoints[panel.number()], col="red", pch=15)
}
xyplot(yield~year|site, data=barley, panel=panelfn)

Regards,
Richie.

Mathematical Sciences Unit
HSL


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