Common legend for two plots
 
With layout  Impossible to put a common title correctly   layout(mat=matrix(c(3, 1, 4, 2), ncol=2), heights = c(10, 90))   par(mar=c(4, 4, 1, 1)+0.4)  plot(x = 1, y = 1, ylim = c(0, 2), xlim = c(0, 2), bty="n")  points(x = 2, y = 2, col = "red")   plot(x = 2, y = 2, ylim = c(0, 2), xlim = c(0, 2), bty="n")  points(x = 1, y = 1, col = "red")   par(mar=c(0, 0, 0, 0)+0)  plot.new()  text(x=1, y=0.5, labels = "Common title", cex=2, pos=2)  plot.new()  text(x=0, y=0.5, labels = "for both graphics", cex=2, pos=4)  layout(1)       With par(fig=c(x1, x2, y1, y2))  It is more easy to set up exact position of ploting region   # restore all par() values to their defaults  dev.off()  plot.new()  par(fig=c(0, 0.5, 0, 0.9))  par(mar=c(4, 4, 1, 1)+0.4)  plot(x = 1, y = 1, ylim = c(0, 2), xlim = c(0, 2), bty="n")  points(x = 2, y = 2, col = "red")   par(fig=c(0.5, 1, 0, 0.9), new = TRUE)  par(mar=c(4, 4, 1, 1)+0.4)  plot(x...
