From: Derick Schoonbee (schoonbee@hotmail.com)
Date: Fri 26 Dec 2003 - 22:50:01 EST
Message-id: <Law11-F122IE3K8TM4F00067cc5@hotmail.com>
Thanks for the reply. The results are exactly the same as what I'm getting.
Now I'm thinking in the lines of:
z1 <- outer(x, y, f)
z2 <- -outer(x, y, f)
So, I want to attach the two hemispheres. But then I need to figure out how
append vectors z1 & z2 and then 'feed' this to persp..
hmm, I'll look into it.
Regards,
D.
From: Spencer Graves <spencer.graves@pdf.com>
To: Derick Schoonbee <schoonbee@hotmail.com>
CC: r-help@stat.math.ethz.ch
Subject: Re: [R] Plot a sphere
Date: Thu, 25 Dec 2003 17:38:01 -0800
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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