[R] persp and lines()

Jeff Jorgensen jcjorgensen at wisc.edu
Wed Feb 18 16:10:27 CET 2004

```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.
> >
> >
> > Cheers,
> >
> > Jeff
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
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