[R] lattice: column titles using xlab.top in multipanel xyplot

[Peter Ehlers]

On 2013-02-25 07:47, Manuel Kunz wrote:
> Hi,
>
> I created a xyplot with a three-column layout. As suggested by Deepayan I tried to put titles to each column by using xlab.top. Unfortunately, as my y-axis scale relation = "free", the column titles are not centered at the three x axes anymore. Any idea how to center the titles?
>
> #Example:
> require(lattice)
> #require(latticeExtra)
> e <- data.frame(a = c(1:30), b = c(1:10,  20:29, 990:999),
>                  d = c(rep("A", 10), rep("B", 10), rep("C", 10)))
> #column titles centered for relation = "same"
> xyplot(b ~ a | d, e,
>         scales = list(y = list(relation = "same", rot = 0)),
>         aspect = 1.8, layout = c(3, 1),
>         xlab.top = c("This is centered", "Bla", "Bla")
>         )
> #column titles not centered for relation = "free"
> xyplot(b ~ a | d, e,
>         scales = list(y = list(relation = "free", rot = 0)),
>         aspect = 1.8, layout = c(3, 1),
>         xlab.top = c("This is not centered", "Bla", "Bla")
>         )
> # end of example
>
> Best regards,
> manuel

If this is a one-off, then I would just add a sufficient number of
spaces, obtained by trial and error, to each label.

On the other hand, why not use lattice's built-in facility to put
your labels in the top strips, using the factor.levels argument.
But perhaps your real use is more involved than the example.

Peter Ehlers