if (FALSE) {
libs(agridat)
data(petersen.sorghum.cowpea)
dat <- petersen.sorghum.cowpea
# Petersen figure 10.4a
tmp <- dat
with(tmp, plot(srows, syield + cyield,
col="blue", type='l', xlim=c(0,5), ylim=c(0,4000)) )
with(tmp, lines(srows, syield) )
with(tmp, lines(srows, cyield, col="red") )
title("Cow Pea (red), Sorghum (black), Total (blue)")
title("petersen.sorghum.cowpea", line=0.5)
}
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