R help - Apr 2011 - lattice wireframe with logarithmically scaled axis?

Hi,

I have some questions for the wireframe function of the lattice package. My
dataset's "x-data" are sampled logarithmically and as such I would
like to have a semilogarithmic 3D plot when plotting a time series. Does anyone
know how to change the example in
http://addictedtor.free.fr/graphiques/sources/source_40.R
such that x or y would be logarithmically scaled?

Also, I would like to change the color scale such that it does not scale from
min to max, but from min to a value below max. Is this possible? How?

TIA,
Christian

On Apr 27, 2011, at 6:49 AM, Dr. Meesters, Christian wrote:
> Hi,
>
> I have some questions for the wireframe function of the lattice  
> package. My dataset's "x-data" are sampled logarithmically
and as
> such I would like to have a semilogarithmic 3D plot when plotting a  
> time series. Does anyone know how to change the example in
> http://addictedtor.free.fr/graphiques/sources/source_40.R
> such that x or y would be logarithmically scaled?
The scales information in help(wireframe) refers you to the  
corresponding section of help(xyplot) where an example of changing the  
scales to logarithmic base 2 on the x axis is presented. A  
modification to the arguments in your example restricted to the  
positive-positive quadrant succeeds:

 > require(lattice)
 >
 > x <- seq(0.001, pi, len = 20)
 > y <- seq(0.001, pi, len = 20)
 > g <- expand.grid(x = x, y = y)
 > g$z <- sin(sqrt(g$x^2 + g$y^2))
 > print(wireframe(z ~ x * y, g, drape = TRUE, scales=list(x =  
list(log = 10)),
+                 aspect = c(3,1), colorkey = TRUE))
>
> Also, I would like to change the color scale such that it does not  
> scale from min to max, but from min to a value below max. Is this  
> possible? How?
>
> TIA,
> Christian
-- 
David Winsemius, MD
West Hartford, CT