[R] How to automatically placing a legend in empty space

[Jason Rupert]

(Sorry if this goes up to the site twice.  I guess I am still learning how to post to R-Help)

At one point I believe I heard of an R package that would automatically find the most empty space in a plot, and then that answer could then be used to intelligently place a legend. 

I would like to try to apply that R package to the contrived example shown below, so thank you for any hints or tips that can be provided.   

x = seq(0, 1000, by = 1)
y1_vals<-rnorm(1000, mean = 0, sd = 50)
y2_vals<-rnorm(1000, mean = 25, sd = 40)
y3_vals<-rnorm(1000, mean = 115, sd = 40)

plot(x_vals, y1_vals, pch=22, col="dark red", bg = "dark red", cex =0.3)
points(x_vals, y2_vals, pch=22, col="dark blue", bg = "dark blue", cex =0.3)
points(x_vals, y3_vals, pch=22, col="dark green", bg = "dark green", cex =0.3)

abline(h=0, col="dark red", lwd=1.5, lty=6)
abline(h=25, col="dark blue", lwd=1.5, lty=6)
abline(h=115, col="dark green", lwd=1.5, lty=6)

legend("topright", c("Best Guess 1" , "Best Guess 2", "Best Guess 3"), bg="white", lwd = 2, title = "Randomness:")