[R] crosshair in scatterplot to mark special points

[Barry Rowlingson]

Mike R wrote:
> In a plot on an X11 device,  I'd like to mark a few points with 
> a large thin "crosshairs".  By "mark" I mean: draw the crosshair
> on the plot.
> 

  Try using the numerical pch symbols. '3' is a crosshair, so see what 
the following do:

  plot(1:10,pch=3)
  plot(1:10,pch=3,cex=2)
  plot(1:10,pch=3,cex=4)

They're probably documented somewhere, but:

  plot(1:26,pch=1:26,cex=2)

  will show you them.

Baz