[R] Specifying point symbol fill colour in lattice xyplot keys

[Wayne Rochester]

Dear all,

When defining explicit keys with xyplot, I have previously used the fill 
parameter to set the background colour of point symbols. That's no 
longer working for me, and I am wondering whether it's a bug or whether 
I've misinterpreted the documentation and have been relying on a feature 
wasn't intended. If the latter, can anyone suggest the correct way to do it?

Here's an example of what I am trying to do:

library(lattice)

print(xyplot(y ~ x,
              data=data.frame(x=1:10, y=1:10),
              key=list(points=list(pch=21,
                                   col="blue",
                                   cex=3,
                                   fill="red"))))

Only the key is of interest here. It doesn't match the data and isn't 
meant to.

On R 2.15.2 and lattice 0.20-10 the circle in the key has a blue outline 
and a red fill colour. On R 2.15.3 and lattice 0.20-13 the fill is 
transparent (or white).

The source code for draw.key looks like it is sill trying to support the 
fill option. I have been able to confirm the old behaviour with the old 
R and lattice versions on Ubuntu 11.10 and openSUSE 12.2. I have 
confirmed the new behaviour with the new versions on Ubuntu 11.10 and 
Windows 7.

Many thanks,

Wayne Rochester
CSIRO, Brisbane, Australia