[R] Adding different output to different lattice panels

[hadley wickham]

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"

It's quite easy to do this with ggplot2 (http://had.co.nz/ggplot2) -
see http://had.co.nz/ggplot2/geom_vline.html for examples of both
common and specific reference lines.

Hadley