Ideas... not a solution. Plot the grid within your ranges using
something along the lines, literally and figuratively, based on the
second example of persp's help pages. For the z=8 grid lines on that
example you could use:
for (ix in seq(-10,10, by=5)) lines (trans3d(x=ix, y=seq(-10,10,
by=5), z= 8, pmat = res),
col = "red",
lty="dotted")
for (iy in seq(-10,10, by=5)) lines (trans3d(x=seq(-10,10, by=5),
y=iy, z= 8, pmat = res),
col = "red",
lty="dotted")
#for some reason using x and y in the for-loops "contaminated" the x
and y values in the calling environment. I did not think that was
supposed to happen.
The concern I see is that the height of the lines and the relation to
the surface is not apparent to the viewer and the the persp function
says it ignores transparent colors. I find that contour plots are less
ambiguous and that the persp plots are most useful for qualitative
shapes rather than quantitative extraction of inferences. Perhaps in
your example (not provided) you could draw the grid lines somewhat
lower and then re-plot plot the surface after plotting the gridlines.
Since I have not mastered the manner in which persp can be convinced
to not plot over an existing device in the regions where it has no
surface, I cannot provide the final steps of that process. The par
help page describing new= does not make sense to me, and trying both
TRUE and FALSE fails to achieve the desired results.
One guess is that the way forward might be to adapt the example the
Sarkar provides at the end of his Lattice book with Figure 13.7:
http://lmdvr.r-forge.r-project.org/figures/figures.html
Or to condition the width of line segments on whether or not they were
above or below the z-value at z[x=seq(),iy] or <something else>.?
--
David Winsemius
On Mar 14, 2009, at 12:02 PM, Pedro Mardones wrote:
Dear all;
Does anyone know how to add grid lines to a persp plot? I've tried
using lines(trans3d..) but the lines of course are superimposed into
the actual 3d surface and what I need is something like the plot shown
in the following link:
http://thermal.gg.utah.edu/tutorials/matlab/matlab_tutorial.html
I'll appreciate any ideas
Thanks
PM
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT
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