Legend formatting in R - what goes wrong?

Question

I am trying to get a correct legend for a series of points in a plot, which look like:

plot(c(3,1),pch=21,bg="white",col="black")
points(c(2,1),pch=21,bg="black",col="black")
points(c(1,1),pch=21,bg="dark grey",col="black")

I thought the legend code would be:

legend("topright",legend=c('Point3','Point2','Point1'),pch=c(21,21,21),
       bg=c('white','black','dark grey'),col=c('black','black','black'),bty='n')

But apparently I am wrong, because I only get three white points with black boarder. Why isn't this working and what is the correct code?

Answer 1

If you read help("legend") you find out that bg specifies the background of the legend. You need to use pt.bg:

legend("topright", legend=c('Point3','Point2','Point1'), pch=c(21,21,21),
     pt.bg=c('white','black','dark grey'), col=c('black','black','black'), bty='n')