[R] bwplot: how to display response variables separately in same panel?

[Deepayan Sarkar]

On 2/8/06, Chris Behr <cbehr at edesigndynamics.com> wrote:
> Hi -
>
> I have two response variables 'y1' and 'y2' and a factor 'x'. I would like
> to create paired box-whiskers plots for y1~x and y2~x and labeled for the
> same x. the b-w plots would be side-by-side in the same panel - almost like
> a barchart with two parallel columns for the same x.
>
> the code 'bwplot(y1+y2~x, outer=T)' gives me two side-by-side panels. this
> is ok, but not exactly what i am looking for.
> any ideas?

Unless you want to write your own panel function, you need to start by
coercing the data into the `long' format, e.g.

df <- data.frame(y = c(y1, y2), x = rep(x, 2), which = gl(2, length(x)))

Then you can probably do [untested]

bwplot(y ~ which | x, df, layout = c(nlevels(x), 1))

or

bwplot(y ~ x:which, df)

Deepayan