[R] Re : how to plot select points in preexisting persp plot

Duncan Murdoch murdoch at stats.uwo.ca
Tue Feb 23 19:15:24 CET 2010

On 23/02/2010 6:01 AM, Preeti Iyer wrote:
> Hello,
> I have a set of points (x and y coordinates) generated by 
> multidimensional scaling function (isoMDS) . The z-axis coordinates 
> consists of a set of values for each of these x and y coordinates. I use 
> persp function to give a surface. What I would like to know is, how I 
> can use the z-coordinates to plot a text label for select points on this 
> surface?

See ?trans3d and ?persp.  Basically, do something like this:

pmat <- persp( .... )
text(trans3d( x, y, z, pmat), text=...)

This won't handle hiding text that falls behind things, but it should 
work in simple cases.   Another option is to use persp3d and text3d from 
the rgl package.

Duncan Murdoch

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