Draw a circle on a filled.contour() plot

On 12/17/2006 9:31 AM, Webmaster wrote:

The output produced by 'filled.contour' is actually a combination
     of two plots; one is the filled contour and one is the legend.
     Two separate coordinate systems are set up for these two
     plots, but they are only used internally - once the function
     has  
returned
     these coordinate systems are lost.  If you want to annotate
     the main contour plot, for example to add points, you can
     specify graphics commands in the 'plot.axes' argument.  An
     example is given below.

Thanks!

I now have another question (hopefully the last) for which I
couldn't  find an answer in the mailing-list archives: how can I get
rid of the  color key on the contour.filled() plot? I that question,
unanswered,  in a post one year ago on this same list, so I hope
it's by any mean  possible... (I think it's possible to change the
code completely and  use image(), but it's much less pretty).

I don't see any option in there, so you might have to write your own
version to do it.  The source for the regular function is in

http://svn.r-project.org/R/trunk/src/library/graphics/R/filled.contour
.R

and the part that plots the key is

     ## Plot the 'plot key' (scale):
     mar <- mar.orig
     mar[4] <- mar[2]
     mar[2] <- 1
     par(mar = mar)
     plot.new()
     plot.window(xlim=c(0,1), ylim=range(levels), xaxs="i", yaxs="i")
     rect(0, levels[-length(levels)], 1, levels[-1], col = col) if
     (missing(key.axes)) {
         if (axes)
             axis(4)
     }
     else key.axes
     box()
     if (!missing(key.title))
 key.title

You'd probably also want to change the layout, because you won't want
the blank space there.  Or possibly you could get the results you want
from contour(), which doesn't plot the scale.

Duncan Murdoch