lattice xyplot, get current level

Hi

xyplot(y ~ x | subject) plots a separate graph of y against x for each
level of subject. But I would like to have an own function for each
level. Something like

xyplot(y ~ x | subject,
      panel = function(x,y) {
        panel.xyplot(x,y)

        panel.curve(x,y) {
          # something that dependents on the current subject
          ...
        }
      })

This seems to be different question than what you later requested. This question would seem to be documented in the 'panel' section of help(xyplot) in particular the paragraph beginning with this sentence:

"One can also use functions called panel.number and packet.number, representing panel order and packet order respectively, inside the panel function (as well as the strip function or while interacting with a lattice display using trellis.focus etc). "

David Winsemius, MD
Alameda, CA, USA