R help - Aug 2003 - levelplot and points

Hi all,

I face the following problem. 

I have two variables x,y. I have also calculated the surface z.
When I am drawing the surface with function >levelplot (in library lattice) 
everything is OK. I have the legend etc ...

Then I am trying to plot x,y on the same graph. So I am doing
:
>points(x,y)
But, the points are not in the correct position. They are a little bit shifted
to the left..(i think)

Any suggestions are really appreciated. 

Regards,
Theodore

Theodore Kypraios, Postgraduate Student
===============================================Web: 
http://www.maths.lancs.ac.uk/~kypraios
email: t.kypraios@lancaster.ac.uk

Department of Mathematics and Statistics
Fylde College
Lancaster University
Lancaster, LA1 4YF
UK
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Don't attempt mix lattice and base graphics, and you cannot add to lattice 
graphics after they have been plotted.
>From MASS4:
levelplot(pred ~ x * y, topo.plt, aspect = 1,
   at = seq(690, 960, 10), xlab = "", ylab = "",
   panel = function(x, y, subscripts, ...) {
      panel.levelplot(x, y, subscripts, ...)
      panel.xyplot(topo$x,topo$y, cex = 0.5, col = 1)
   }
)

to add points to a levelplot.

On Tue, 5 Aug 2003, Theodore Kypraios wrote:
> I face the following problem. 
> 
> I have two variables x,y. I have also calculated the surface z.
> When I am drawing the surface with function >levelplot (in library
lattice)  everything is OK. I have the legend etc ...
> 
> Then I am trying to plot x,y on the same graph. So I am doing :
> >points(x,y)
> 
> But, the points are not in the correct position. They are a little bit
shifted to the left..(i think)
> 
> Any suggestions are really appreciated. 
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595