[R] Plot a sphere

[Derick Schoonbee]

Uwe,

Thanks, I installed it and ran:

rgl.spheres(rnorm(10),rnorm(10),rnorm(10),radius=1,color=rainbow(10))

Nice :)

Thus, I'll give rgl a try but still would be 'stuborn' to see if I can 
figure a way out to use persp.

Regards,
D.


From: Uwe Ligges <ligges at statistik.uni-dortmund.de>
To: Spencer Graves <spencer.graves at pdf.com>
CC: Derick Schoonbee <schoonbee at hotmail.com>,r-help at stat.math.ethz.ch
Subject: Re: [R] Plot a sphere
Date: Fri, 26 Dec 2003 12:48:49 +0100



Spencer Graves wrote:
 >
 >       A hemisphere is relatively easy;  try the following:
 >
 >       x <- seq(-1, 1, length=21)
 >       Z <- outer(x, x, function(x, y)sqrt(1-x^2-y^2))
 >       persp(x=x, y=x, z=Z)
 >
 >       A contour plot is also relatively easy:
 >
 >       image(x=x, y=x, z=Z)
 >       contour(x=x, y=x, z=Z, add=T)
 >
 >       However, if you want an honest perspective plot of a sphere
 > complete with the underside, etc., I know of nothing in R that could do
 > that.  S-Plus has "perspp", which could be used.  However, that seems to
 > be one of the few features available in S-Plus that is not currently
 > available in R.


The R package "rgl" by Adler and Nenadic can plot spheres. It is
available at
http://wsopuppenkiste.wiso.uni-goettingen.de/~dadler/rgl/
  --- and looks like it will shortly become a CRAN package.

Uwe Ligges


 >        hope this helps.
 >       spencer graves
 >
 > Derick Schoonbee wrote:
 >
 > > Hi,
 > >
 > > I'm new to R (and math ;) Would somebody please be so kind as to
 > > direct me in plotting a 3D sphere?
 > >
 > > I tried something in the lines of:
 > > ####
 > > y <- x <- seq(-pi, pi, length=pi*10)
 > > f <- function(x,y)
 > > {
 > >     z <- sqrt(pi - x^2 - y^2)
 > >     #z[is.na(z)] <- 0
 > >     z
 > > }
 > > z <- outer(x, y, f)
 > >
 > > persp(x, y, z, theta = 120, phi = 30)
 > > ####
 > >
 > > I've also tried: .... make.surface.grid(...) .. persp( as.surface(
 > > grid, z) ) ... with the same result: 'Incomplete' demi sphere and
 > > others..
 > >
 > > Any suggestions/solutions would be appreaciated.
 > >
 > > Regards,
 > > Derick
 > >
 > > PS:Merry X-mas ;)
 > >
 > > ______________________________________________
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 >
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