labels_in_panels.R

set.seed(12345)
dat <- data.frame(category=rep(c("Food", "Drinks"),20),
                  product=rep(c("Cheese", "Wine", "Bread", "Beer"), 10),
                  year=sort(rep(c(2004:2013),4)),
                  value=sort(rnorm(40)))

dat <- dat[with(dat, order(category, year)),]

library(lattice)
# Change some of the default lattice settings
my.settings <- canonical.theme(color=FALSE)
my.settings[['strip.background']]$col <- "black"
my.settings[['strip.border']]$col<- "black"
xyplot(value ~ year | category, 
       groups=product, data=dat, 
       as.table=TRUE, 
       xlim=c(2003, 2016),          # range of x-axis
       scales=list(cex=c(1.1, 1.1), # increase font size
                   alternating=1,   # axes labels left/bottom 
                   tck = c(1,0)),   # ticks only with labels
       par.settings = my.settings, 
       cex=1.1, # change size of symbols 
       xlab=list(label="Year", fontsize=14),
       ylab=list(label="Value", fontsize=14),
       par.strip.text=list(col="white", font=2),       
       panel=panel.superpose,
       panel.groups=function(x,y, group.number,...){           
         panel.xyplot(x,y,t="b",...) 
         panel.grid(v=-1, h=-1, lty=3)
         xt <- x[x==max(x)] # find latest year
         yt <- y[x==max(x)] # find value at latest year         
         panel.text(xt, yt, labels=levels(dat$product)[group.number], 
                    pos=4,  # show labels on right side
                    ...)
       }              
)