How to label panels in lattice

Question

here is a simple problem that surely you already come across, but is giving me a big headache...

I have a dataframe like this:

set.seed(3)
mydata <         


        

Answer 1

You almost got it. If you need letters, then index letters with panel.number():

xyplot(var ~ temp | subj, 
   data = mydata,
   strip=FALSE,
   panel = function(x, y,...) {
           panel.xyplot(x, y,...)
           panel.text(1,21,labels=letters[panel.number()])
           }) 

You can also define another character vector inside your panel function and use this indexing schema with it.