# NOT RUN {
data(theobald.barley)
dat <- theobald.barley
dat <- transform(dat, env=paste(loc,year,sep="-"))
dat <- transform(dat, income=100*yield - 400*nitro/1000)
require(lattice)
xyplot(income~nitro|env, dat, groups=gen, type='b',
auto.key=list(columns=3), main="theobald.barley")
# }
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