# NOT RUN {
data(blackisland)
print(head(blackisland,20))
oldpar <- par(no.readonly=TRUE)
plot(blackisland$l1,blackisland$dl,type="p",pch=16,
xlab="Initial Length mm",ylab="Growth Increment mm",
panel.first=grid())
abline(h=0)
par(oldpar)
# }
Run the code above in your browser using DataLab