Calling xyplot from inside a function.

["Paul Lasky" <phlasky@earthlink.net>]

 I know this is another tiresome "scoping" question, but I can't seem to get a Trellis plot with panel functions to work when called from a function:

 

  What I want to do is graph prob density, put some quantile vertical lines on the graph, and place some text on the graph labeling the vertical lines; the following code (without attempting the labeling) doesn't work:

 

  myFunction = function( obj ) {

     #

     den = density( obj$score, n=100, width = 29 )

     quant = quantile( obj$score, c( 0.1, 0.5, 0.9 ) )

     main2 = "My Stuff"

     #

      xyplot( den$y ~ den$x, xlab="Points", type = "l",main = main2, col  = 1,

        panel = function(x, y) {

           panel.abline( v  = quant, lty = 2 )

        }

     )   

  }

   Also what is the code for Labeling the vertical  quantile lines with text at the bottom such as " 10%", "Median", "90%"? 

  A panel.text function isn't available.

 

Producing this plot within a function is easy to do with the old-fashioned plot function. But Trellis plots seem to be so  difficult to work with that, frankly, most of the time they aren't worth the effort.  In this instance, however it would be desirable from a publication standpoint to produce a Trellis plot. 

 

Paul Lasky

P & B Consultants.