[R] Plot a sphere

[Uwe Ligges]

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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> > https://www.stat.math.ethz.ch/mailman/listinfo/r-help
> 
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