Desktop Survival Guide
by Graham Williams

Legends and Points

The legend function is used to add a legend to a plot. A specific coordinate can be given as the first two arguments, or else a symbolic location, such as topleft and center, can be given. The Roption[]pch option specifies a plotting symbol, and the first 25 (1:25) are shown on the plot below. Other symbols are available in the 32:255 range. The Roption[]lty is used to specify line types. The Roption[]col is used to specify colours.

Image rplot-legends

plot(1:10, rep(7.5,10), ylab="", ylim=c(1,10), xlim=c(1,10), pch=1:10, col=1:10)
points(1:10, rep(7,10), pch=11:20, col=11:20)
points(1:5, rep(6.5,5), pch=21:25, col=21:25)
legend("topleft", "topleft pch 1", pch=1)
legend("top" , "top pch 2", pch=2)
legend("topright", "topright pch 3", pch=3)
legend("left", "left pch 6", pch=6)
legend("center", "center pch 7", pch=7)
legend("right", "right pch 8", pch=8)
legend("bottomleft", "bottomleft pch 10", pch=10)
legend("bottom", "bottom pch 11", pch=11)
legend("bottomright", "bottomright pch 12", pch=12)
legend <- c("topleft pch 4", "inset pch 5")
legend("topleft", legend, inset=c(0.1, 0.1), pch=c(4,5))
legend(2, 3, legend="point (2,3) pch 9", title="title", pch=9)
plen <- length(palette())
legend(5.5, 4.5, palette(), lty=1:plen, col=1:plen, ncol=2)

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