[R] Lattice : Single reference line/label at 0.05

[Deepayan Sarkar]

On 6/30/08, Troy S <troysocks-twigs at yahoo.com> wrote:
> r-friends--
>
>  I am trying to make a lattice plot with a single label at 0.05.  A reference line at y=0.05 as well...  This is what I have so far.  The label reads 0.0 and there is a grid instead of a single reference line.  Can someone help please?
>
>  Troy
>  x<-18:35
>  (pv<-1/(x-17))
>  xydf<-data.frame(x, pv)
>  print(xyplot(pv~x, data=xydf, type=c('p', 'g'),
>   ylim=c(0,1),
>   yscale.components= function(lim, ...) {
>     ans <- yscale.components.default(lim = lim, ...)
>     ans$left$ticks$at <- c(0.05)
>     ans$left$ticks$labels$at <- c(0.05)
>     ans$left$ticks$labels$labels <- c("0.05")
>     ans
>     }
>
>   ))

You probably meant to do

print(xyplot(pv~x, data=xydf, type=c('p', 'g'),
 ylim=c(0,1),
 yscale.components= function(lim, ...) {
   ans <- yscale.components.default(lim = lim, ...)
   ans$left$ticks$at <- c(0.05)
   ans$left$labels$at <- c(0.05)
   ans$left$labels$labels <- c("0.05")
   ans
   }
 ))

but this is simpler:

xyplot(pv~x, data=xydf, type=c('p', 'g'), ylim = c(0, 1),
         scales = list(y = list(at = 0.05)),
         panel = function(...) {
             panel.abline(h = 0.05)
             panel.xyplot(...)
         })

-Deepayan