[R] Plots with discontinuity balls

[Paul Smith]

On 9/28/07, Duncan Murdoch <murdoch at stats.uwo.ca> wrote:
> > Can R plot graphs like the one at
> >
> > http://www.mathwords.com/f/f_assets/floor_graph.gif
> >
> > with the balls at the discontinuity points?
>
> You can use segments() to draw the segments and symbols() to draw the
> balls.  For example,
>
> plot(1,1,type='n', xlim=c(1,10), ylim=c(1,10))
> segments(1:9, 1:9, 2:10, 1:9)
> symbols(2:10, 1:9, circles=rep(0.1,9), inches=FALSE, bg="white",add=T)
> symbols(1:9, 1:9, circles=rep(0.1,9), inches=FALSE, bg="black",add=T)
>
> This depends on the order of drawing, because the white background of
> the first circles obscures the ends of the segments.

Thanks, Jim and Duncan. It would help to have transparent backgrounds
for the white balls.

Paul