[R] wireframe zlim option

[Marius Hofert]

Hello,

I would like to plot a wireframe of a function which is defined on the
unit square using the lattice library (for trellis-like plots). The plot
contains z-values of about 100 (only in the neighborhood of zero) although
most of the z-values are in the range of -let's say- 0 to 10. If I
evaluate this function on an equidistant grid of 25 points on the unit
square the plot quality is not very good, but I can see the rough shape of
the plot (i.e. I can see the that the points in the range of 0 to 10 have
different heights). If I increase the grid points to 100 (so the function
is evaluated on an equidistant grid with 100^2 points), the plot quality
increases (i.e. the plot gets smooth), but I can hardly see any structure
of the plot as the points in the neighborhood of zero of course dominate
the plot (and all points in the range from 0 to 10 seem to just have the
same height) and as I evaluate more of the points close to 0 this behavior
is obvious. Therefore I would like to restrict the z-values plotted. I
couldn't find any help for that and the usual "zlim=c(0,30)" (which should
only plot the z-values lying in the range from 0 to 30) did not work for
the wireframe function of the lattice package.
The call I tried was

>library(lattice)
>wireframe(z~x*y,zlim=c(0,30),drape=T,distance=0,colorkey=list(tick.number=6))

Any hints are appreciated

Thanks in advance

Marius

mhofert at mathematik.uni-ulm.de