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

[Deepayan Sarkar]

On 5/15/08, RINNER Heinrich <HEINRICH.RINNER at tirol.gv.at> wrote:
> 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.

You could borrow from 'strip.default' to modify your strip function as follows:

strip.left.aligned <- function(which.given, which.panel, factor.levels, ...) {
    require(grid)
    pushViewport(viewport(y = (which.given - 0.5)/length(which.panel),
                          height = 1/length(which.panel),
                          clip = trellis.par.get("clip")$strip,
                          name = paste("strip.default", which.given,
sep = ".")))
    panel.rect(0, 0, 1, 1,
               col = trellis.par.get("strip.background")$col[which.given],
               border = 1)
    panel.text(x = 0, y = 0.5, pos = 4,
               lab = factor.levels[which.panel[which.given]])
    upViewport()
}

This would also make it useful with multiple conditioning variables, e.g.,

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

-Deepayan

>  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
>  >
>  >
>  >
>  >
>  >
>
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