[R] help with strip.default

[Deepayan Sarkar]

On 1/6/06, Berton Gunter <gunter.berton at gene.com> wrote:
> Steve:
>
> This is a question for **super Deepayan,** and hopefully he'll respond.
>
> However, in the interim, let me give it a shot. Basically, I think what
> you've asked for falls outside the bounds of what lattice is designed to do.
> But I think there's a simple way to fool it. Basically what you need to do
> is to combine your two factors into one with level names and ordering as you
> want. See ?factor (?ordered may also be useful, but you don't need it). For
> example:
>
> comb.factor=factor(paste(A,B,sep='.'))

That's what I would have suggested. I would recommend using
interaction() instead of paste(), since it is designed for this and is
presumably more efficient (not that it matters in this small example).
For the record, the 'layout' and 'skip' arguments (of xyplot etc) are
often useful in conjunction with this sort of use.

Deepayan

> As I said, you may have to reorder the levels from the default that factor()
> gives you to get your panels to display the way you want. Also see the
> perm.cond and index.cond arguments of xyplot, which might also suffice for
> that purpose.
>
> Again, Deepayan will hopefully suggest a cleverer way that I missed. But I
> think this approach will get you what you want.
>
> Cheers,
> Bert
>
> -- Bert Gunter
> Genentech Non-Clinical Statistics
> South San Francisco, CA
>
> "The business of the statistician is to catalyze the scientific learning
> process."  - George E. P. Box
>
>
>
> > -----Original Message-----
> > From: r-help-bounces at stat.math.ethz.ch
> > [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Steven Lacey
> > Sent: Friday, January 06, 2006 8:20 AM
> > To: r-help at stat.math.ethz.ch
> > Subject: [R] help with strip.default
> >
> > Hi,
> >
> > I am creating a multi-conditioned trellis plot. My data look
> > something like
> > this:
> >
> > Factor A    Factor B    IV    DV
> > X           1
> > X           2
> > X           3
> > X           4
> > Y           1
> > Y           2
> > Y           3
> > Y           5
> > Z           1
> > Z           2
> > Z           3
> > Z           4
> >
> > In one sense these data are suitable for trellis because for
> > every level of
> > factor A there are four levels of factor B. However, the
> > names of the factor
> > B levels depend on the level of factor A.
> >
> > How would I create a 3 x 4 trellis plot where each panel is a
> > combination of
> > factor A and factor B where the names of factor B are
> > preserved and the
> > strip has two levels, one for factor A and another for factor B?
> >
> > This was more difficult than I thought because trellis wants
> > to generate 15
> > panels, as there are 3 levels of factor A and 5 levels of
> > factor B. But
> > these 5 levels of factor B are in name only. There are only 4
> > different
> > levels of factor B for each level of factor A.
> >
> > As a work around I am considering renaming the levels in
> > factor A from 1 to
> > 4 for all levels of factor B. Then, write a custom
> > strip.default to specify
> > the names. However, I am not sure how to write this function.
> > Would someone
> > help me get started?
> >
> > Thanks,
> > Steve