From: Spencer Graves (spencer.graves@pdf.com)
Date: Fri 26 Dec 2003 - 12:38:01 EST
Message-id: <3FEB90F9.8010509@pdf.com>
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.
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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