Skip to content

persp and lines()

4 messages · Jeff Jorgensen, Tom Blackwell, Spencer Graves

Jeff Jorgensen
# 
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
Tom Blackwell
# 
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:

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Spencer Graves
    

    

      
      #
    

  


  

      
The help file for persp (in R 1.8.1, at least) includes a function 
to "Add to existing persp plot".  Have you tried that?  Alternative, 
have you considered "wireframe" in package lattice? 

      hope this helps.  spencer graves

        
Jeff Jorgensen wrote:

        

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Jeff Jorgensen
    

    

      
      #
    

  


  

      
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: