What does persp() return?
David Brahm wrote:
Thanks very much to Paul Murrell, Ben Bolker, and Peter Dalgaard for
responding. Sorry I failed to find the 3/15/02 discussion of this same topic.
May I suggest that the omission of the returned value from the help page for
persp() is a "documentation bug"? Something like this could be added:
Value:
A 4x4 matrix (call it "pmat"), suitable for transforming 3D coordinates
(x,y,z) into list(x,y) values. These can then be used by lines(), points(),
etc, to superimpose additional data on the 3D plot. The transformation can be
accomplished with the following function:
trans3d <- function(x,y,z, pmat) {
tmat <- t(cbind(x,y,z,1) %*% pmat)
list(x=tmat[1,]/tmat[4,], y=tmat[2,]/tmat[4,])
}
I must have missed the beginning of this thread. After the mentioned similar discussion from march, I hacked (I mean: *hacked*) a function s3d.persp() that combines persp() with some of the ideas from scatterplot3d(). s3d.persp() was included in one unpublished (in a way) version of the package scatterplot3d, which is available at: http://www.statistik.uni-dortmund.de/leute/ligges/R/scatterplot3d/scatterplot3d_0.3-10.tar.gz respective http://www.statistik.uni-dortmund.de/leute/ligges/R/scatterplot3d/scatterplot3d_0.3-10.zip for the windows version. Well, because of the hughe differences in the design of those functions won't fit together easily. Since no clean solution can be found quickly, I throw s3d.persp() away one day later, but it might be useful for you anyway. Uwe Ligges -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._