Rule for accessing attributes?

 xydf <- data.frame(x = 1:5, y = 11:15)
 plt <- ggplot(data = xydf, aes(x = x,y = y)) + geom_point()
 attributes(plt)

 Now we can change the title:

 plt$title <- "My Title"
 plt

This is rather poorly documented, but the preferred way of setting the
title is now:

p + opts(title = "My Title")

All options should be documented under ?opts (but aren't, unfortunately).

Hadley

http://had.co.nz/