persp and lines()
Tom,
Thanks for the nudge to reexamine the instructions. I wasn't calling the
right object with "pmat". I first had to create a perspective plot object
which creates the plot, and then call *that* object for "pmat", not the
matrix I used to create the plot in the first place:
surface<-persp(x=..., y=..., z=perspmatrix, ....)
## function needed to add things to persp, found in the ?persp help menu ##
trans3d <- function(x,y,z, pmat) {
tr <- cbind(x,y,z,1) %*% pmat
list(x = tr[,1]/tr[,4], y= tr[,2]/tr[,4])
}
lines(trans3d(x=..., y=..., z=..., pmat=surface), ...)
At 07:45 PM 2/17/2004 -0500, you wrote:
Jeff -
See the section titled "Value:" and example (2) from help("persp")
for instructions and an example of doing exactly what you ask.
- tom blackwell - u michigan medical school - ann arbor -
On Tue, 17 Feb 2004, Jeff Jorgensen wrote:
R-sters: I'm interested in keeping data plotted in persp to preserve the wireframe look, I'd just like to change one of the lines drawn (in either the x or y direction) into a different color so that it stands out. Or is there some way to add a line (say, via lines(), or abline()) to a persp() plot at the designated x or y that would follow the z surface contour? I could add a line using 2D representations of the data, but I'd like to use the perspective plot if possible. Any advice? Cheers, Jeff
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