[R] lattice: left-aligned text in strips?

[RINNER Heinrich]

Thanks for your help!
I guess I could have thought for ages about this, and never would such a solution have come to my mind ;-)
It works as far as the text in the strips is left-aligned; a remaining drawback is that printing of longer texts will be continued outside the right border of their strip.
For example, using your suggestion:

###
library(lattice)
test <- data.frame(x=rnorm(100), y=rnorm(100), a=rep(c("A", "B", "C", "D: left-aligned text (possibly looooooooooooooooooooooooooooooooooooooooong string"),25))

strip.left.aligned <- function(which.given, which.panel, factor.levels, ...) {
   panel.rect(0, 0, 1, 1, col = trellis.par.get("strip.background")$col[which.given], border = 1)
   panel.text(x = 0, y = 0.5, pos = 4, lab = factor.levels[which.panel[which.given]])
}

xyplot(y ~ x | a, data = test, strip = strip.left.aligned)
###

Anywag, thanks again for having taken the time thinking about my question;
Heinrich.

> -----Ursprüngliche Nachricht-----
> Von: Charilaos Skiadas [mailto:cskiadas at gmail.com] 
> Gesendet: Mittwoch, 14. Mai 2008 13:30
> An: RINNER Heinrich
> Cc: r-help at stat.math.ethz.ch
> Betreff: Re: [R] lattice: left-aligned text in strips?
> 
> 
> 
> On May 14, 2008, at 3:47 AM, RINNER Heinrich wrote:
> 
> > [adapted repost of question
> > http://tolstoy.newcastle.edu.au/R/e4/help/08/03/6260.html]
> >
> > Dear R community,
> >
> > by default, text in the strips of a trellis plot is centered in the
> > strip.
> > Is there a way to have the text left-aligned?
> >
> > For example:
> >
> > library(lattice)
> > test <- data.frame(x=rnorm(100), y=rnorm(100), a=rep(c("A: centered
> > text","B: centered text"),50))
> > xyplot(y ~ x | a, data = test)  # ok, strip text is centered
> > test <- data.frame(x=rnorm(100), y=rnorm(100), a=rep(c("A: left- 
> > aligned
> > text","B: left-aligned text (possibly 
> loooooooooooooooooooooooooooong
> > string"),50))
> > xyplot(y ~ x | a, data = test)  # how???
> 
> Here's a way to do it, shamelessly stealing the main idea from:  
> http://dsarkar.fhcrc.org/lattice/book/figures.html? 
> chapter=10;figure=10_24
> 
> Mainly you just have to write your own strip function.
> 
> xyplot(Petal.Length~Petal.Width|Species, iris, strip=function 
> (which.given,which.panel, factor.levels,...) {
>    panel.rect(0, 0, 1, 1, col = trellis.par.get("strip.background") 
> $col[which.given], border = 1)
>    panel.text(x = 0, y = 0.5, pos = 4, lab = 
> factor.levels[which.panel 
> [which.given]])
> } )
> 
> Better yet, you should probably write a more generic strip function  
> that does what you want.
> 
> I would however consider using ?abbreviate for what you want to do  
> instead.
> 
> > I am using R 2.6.2 on Windows XP, package lattice Version 0.17-6.
> >
> > [The reason I would like to do this is because "in real life" my
> > conditioning variable 'a' can have quite long strings as 
> its value.  
> > I am
> > automatically creating a series of trellis plots, and in each one a
> > different number of panels will be produced (maybe 4, maybe  
> > 20,...). So
> > in some cases (few panels, short labels) text in the strips will be
> > perfectly readable, while in some cases (many panels, long labels)  
> > only
> > the middle of the text will.
> > I know I could abbreviate the strip text by using something like:
> > xyplot(y ~ x | substr(a,1,35), data = test)
> > But there is no "natural" choice of string length here when 
> I want to
> > cut off as few text as possible, so just left aligning the 
> strip texts
> > would seem like a natural and easy(?) solution to me - if I was  
> > able to
> > do it...]
> >
> > -Heinrich.
> 
> Haris Skiadas
> Department of Mathematics and Computer Science
> Hanover College
> 
> 
> 
> 
>