[R] Adding 3D points

[dhirm001]

I would like to add individual points and lines to a persp() 
plot that I generated with the geoR package. It is a kriged 
surface map of a field plot and I'd like to overlay my 
sampling points on it but am having some trouble. I loaded 
the scatterplot3d package, but I can't seem to use the add 
parameter with it. Any suggestions?

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Re: [R] Adding 3D points

[David Brahm]

[EMAIL PROTECTED] wrote:

 I would like to add individual points and lines to a persp() plot that I
 generated with the geoR package.

See example (2) in ?persp.  You must define this function:
  trans3d - function(x,y,z, pmat) {
tr - cbind(x,y,z,1) %*% pmat
list(x = tr[,1]/tr[,4], y= tr[,2]/tr[,4])
  }

Then you must assign the result of your persp() call to pmat, e.g.:
R x - y - seq(-10, 10, length = 50)
R f - function(x, y) {r - sqrt(x^2+y^2); 10 * ifelse(r==0, 1, sin(r)/r)}
R z - outer(x, y, f)
R pmat - persp(x, y, z, theta=30, phi=30, expand=.5, col=lightblue,
+  xlab=X, ylab=Y, zlab=Z, ticktype=detailed)

And then you can add points and lines:
R points(trans3d(0,0,f(0,0),pmat))
R z2 - sapply(1:length(x),function(n)f(x[n],y[n]))
R lines(trans3d(x,y,z2,pmat),col=red,lwd=2)
R lines(trans3d(c(-10,10,10,-10,-10),c(-10,-10,10,10,-10),c(2,2,8,8,2), pmat),
+col=blue)

All hail to Ben Bolker, who kindly taught me this in March 2002.
-- 
  -- David Brahm ([EMAIL PROTECTED])

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