ggplot2: facet_wrap strip color based on variable in data set

Question

Is there a way to fill the strips of facets created with facet_wrap based on a variable supplied with the data frame?

Example data:

MYdata <- data.f

Answer 1

I would love to know how to do that, it is a great idea. One idea is to generate each chart independently with a different color as you do and then use something like multiplot or viewports to show then side by side - it will require a bit more work.

if you want to extract the legend, which you will need for this approach - here is some code from Hadley that I found a while back

g_legend<-function(a.gplot){
  tmp <- ggplot_gtable(ggplot_build(a.gplot))
  leg <- which(sapply(tmp$grobs, function(x) x$name) == "guide-box")
  legend <- tmp$grobs[[leg]]
  return(legend)}

see how it is extracted it from chart p, and then I took it out of the plot legend <- g_legend(p) lwidth <- sum(legend$width) #if you want to define the viewport based on this p <- p + theme(legend.position="none")

then you eventually draw it

grid.newpage()
vp <- viewport(width = 1, height = 1)
#print(p, vp = vp)

submain <- viewport(width = 0.9, height = 0.9, x = 0.5, y = 1,just=c("center","top"))
print(p, vp = submain)
sublegend <- viewport(width = 0.5, height = 0.2, x = 0.5, y = 0.0,just=c("center","bottom"))
print(arrangeGrob(legend), vp = sublegend)

Good luck