(This article was first published on

If you need to share a common legend between two graphs using the ggplot2 package/paradigm take a look at this post from the Learning R blog.**One R Tip A Day**, and kindly contributed to R-bloggers)The code below solves the same task using the R base graphics.

`png( "2plot1legend.png", width = 480, height = 680)`

par(mfrow = c(2, 1), oma = c(0, 0, 0, 2))

plot(hp~mpg, data=mtcars, col=cyl,pch=19)

plot(disp~wt, data=mtcars, col=cyl,pch=19)

par(xpd=NA)

#legend(locator(1), legend=as.numeric(levels(factor(mtcars$cyl))), pch=19, col= as.numeric(levels(factor(mtcars$cyl))) )

legend(x=5.6, y=690, legend=as.numeric(levels(factor(mtcars$cyl))), pch=19, col= as.numeric(levels(factor(mtcars$cyl))) )

dev.off()

To

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