I am using xyplot from the lattice package, and I want to change the color of hte header. Currently, it is an ugly light-orange color.
library(lattice)
x <- c(1:10, 1:10)
y <- c(10:1, 10:1)
z <- c(1:10, seq(1,20, by=2))
a = c(rep("one",10),rep("two",10))
DF <- data.frame(x, y, z, a)
xyplot(y ~ x | a, groups = z < 5, data = DF, col = c("black", "red"),
pch=20, cex=0.3)