[R] restricting lattice pages to one

[Deepayan Sarkar]

On Thu, Sep 25, 2008 at 7:33 AM, John Fox <jfox at mcmaster.ca> wrote:
> Dear list members,
>
> I'd like to be able to restrict the number of pages in a lattice display to
> one without having to specify explicity the number of rows and columns in
> the display -- that is, having forced one page, I'd like the number of rows
> and columns to be determined automatically.
>
> For example, the following code produces two pages of output, with the
> second replacing the first on the trellis device:
>
>  A <- factor(rep(c("a1", "a2"), c(20, 20)))
>  B <- factor(rep(rep(c("b1", "b2"), c(10, 10)), 2))
>  C <- factor(rep(rep(c("c1", "c2"), c(5, 5)), 4))
>  X <- rnorm(40)
>  Y <- X + 0.2*rnorm(40)
>  trellis.device()
>  xyplot(Y ~ X | A + B + C)
>
> I can get what I want via
>
>  xyplot(Y ~ X | A + B + C, layout=c(4, 2, 1))
>
> but in the application I have in mind, I'd like to avoid having to compute
> the rows and columns.

A general (but two-step) solution is

p = xyplot(Y ~ X | A + B + C)
update(p, layout = c(0, prod(dim(p))))

Another solution that is effectively the same (with different strip
annotation) is to use an interaction as the single conditioning
variable.

xyplot(Y ~ X | A:B:C)

-Deepayan