How to add different text to each panel in lattice

Question

I would like to add different text to each panel in xyplot in lattice.

res<- xyplot(CumSpec ~ CumTotal | Site, data=data1, index.cond=list(c(1,2,3)),layout = c(3,1,1), aspect = 1,
         axis=axis.overlap, origin=0, xlab="Total number of individuals", ylab="Total number of species",
         between = list(x = 0), 
         scales=list(tick.number = 8, cex = .9, x=list(alternating=1), x=list(rot=90)),
         par.settings = my.settings,
         par.strip.text=list(col="white", font=2),
panel = function(x, y) {
panel.xyplot(x, y)

panel.abline(lm(y ~ x), lwd = 0.5, lty=2)
panel.text(400, 4.6, label="R=0.334", font=1)
}) 
res

I have tried to use panel.text but it adds the label to every panel. Does anyone know how to achieve this, please? your help would be appreciated.

Answer 1

The basic strategy you want is to first come up with a character vector, where each element in the vector is the text you want on a particular panel. Then you can use the panel.number() function to chose a different element of the character vector for each panel. Here is a simple example:

library(lattice)
X<-rnorm(100)
Y<-rnorm(100)
Z<-c(rep("A",50),rep("B",50))
df1<-data.frame(X,Y,Z)

MyText<-c("Panel 1 Text", "Panel 2 Text")

xyplot(X~Y|Z, data=df1,
   panel=function(x, y,...){
   panel.xyplot(x,y,...)
   panel.text(0,0,labels=MyText[panel.number()]) }
 )

You could use this strategy for anything you want to change from panel to panel (e.g your x- and y-positions for the labels, colors, pch values, etc).