[R] lattice: adding text to plots

[Deepayan Sarkar]

On 10/9/06, Ritwik Sinha <ritwik.sinha at gmail.com> wrote:
> Hi Gabor,
>
> Thanks for your reply. The solution you gave me and the one that I had
> attempted have the same problem. The plots don't differentiate between
> y1 and y2, in other words, they loose the groups attribute. This is
> what 'does not work' means. I am attaching a ps file (I hope that does
> not get stripped). In each panel there should be two lines, but this
> has just one (group lost).
>
> This plot was produced with R 2.4 on windows and lattice 0.14-9.

Just out of curiosity, what's wrong with

xyplot(y1 + y2 ~ x | interaction(g, h, sep = "-"), data = DF, type =
"l", auto.key = TRUE)

? Not having to do the other sort of callisthenics is the whole point
of having strips.

I should point out a subtle effect here (even hinted at in the
documentation, miraculously), which can be seen with

> xyplot(y1 + y2 ~ x | g * h, data=DF,
+ panel = function(x, y, ..., subscripts) print(subscripts) )
[1]  1  3  5 13 15 17
[1]  7  9 11 19 21 23
[1]  2  4  6 14 16 18
[1]  8 10 12 20 22 24

Note that the last three values of 'subscripts' in each panel is 12 +
i, where i is the true subscript (DF has only 12 rows). This is a
consequence of the fact that DF is internally 'reshape()'d. Gabor's
solution avoids this by using subscripts[1] in each panel (and also
because 'x' and 'y' are not recycled to be as long as the labels in
grid.text), but it's something to be generally aware of.

-Deepayan

>
> Thanks and regards,
> Ritwik.
>
> On 10/9/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > Could you explain what "does not work" means.  It seems to produce a
> > graph with x-y numbers on it in R 2.4.0 on Windows.
> >
> > At any rate, I would have done it like this although I think you can
> > leave off the [1] on subscripts and it will still work.
> >
> > library(lattice)
> > library(grid)
> > xyplot(y1 + y2 ~ x | g * h, data = DF, type = "l",
> >    panel = function(x, y, subscripts, groups, ...) {
> >       panel.xyplot(x, y, ...)
> >       grid.text(DF$f[subscripts[1]], .1, .9)
> > })
> >
> >
> > On 10/9/06, Ritwik Sinha <ritwik.sinha at gmail.com> wrote:
> > > Hi Everyone,
> > >
> > > I know there was a thread recently that dealt with a similar issue,
> > > but this one is a little different.
> > >
> > > I have the following data frame
> > >
> > > DF <- data.frame(x = 1:12, y1 = rnorm(12), y2 = rnorm(12), g =
> > > gl(2,6), h = rep(c("1", "2"), 6), f = c(rep(c("1-1","1-2"),3),
> > > rep(c("2-1","2-2"),3)))
> > >
> > > I essentially want this plot
> > >
> > > xyplot(y1+y2~x|g*h, data=DF, type="l")
> > >
> > > However, now I want to add a different text to each panel, the text
> > > being from column "f" of the data frame. In other words, I want text
> > > "1-1" in the panel where g=1 and h=1 and so on. I tried to pass groups
> > > and subscript to the panel function but could not get what I was
> > > looking for. The following attempt does not work.
> > >
> > > xyplot(y1+y2~x|g*h, data=DF, type="l", auto.key=TRUE,
> > >        panel=function(x,y,..., groups, subscripts){panel.xyplot(x,y,...);
> > >        panel.text(x=4,y=0, labels=DF$f[subscripts])})
> > >
> > > My R version is 2.2.1 and lattice version is  0.12-11 (sorry they are
> > > not the latest ones, these are on the server).