That's interesting. You might also like:
http://en.wikipedia.org/wiki/Von_Mises%E2%80%93Fisher_distribution
I'm not sure how to plot the wireframe sphere, but you can visualize the
points by transforming to Cartesian coordinates like so:
u <- runif(1000,0,1)
v <- runif(1000,0,1)
theta <- 2 * pi * u
phi <- acos(2 * v - 1)
x <- sin(theta) * cos(phi)
y <- sin(theta) * sin(phi)
z <- cos(theta)
library("lattice")
cloud(z ~ x + y)
-Matt
On Fri, 2011-02-25 at 14:21 +0100, Lorenzo Isella wrote:> Dear All,
> I need to plot some points on the surface of a sphere, but I am not sure
> about how to proceed to achieve this in R (or if it is suitable for this
> at all).
> In any case, I am not looking for really fancy visualizations; for
> instance you can consider the images between formulae 5 and 6 at
>
> http://bit.ly/hOgK9h
>
> Any suggestion is appreciated.
> Cheers
>
> Lorenzo
>
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> and provide commented, minimal, self-contained, reproducible code.
Dear All, I need to plot some points on the surface of a sphere, but I am not sure about how to proceed to achieve this in R (or if it is suitable for this at all). In any case, I am not looking for really fancy visualizations; for instance you can consider the images between formulae 5 and 6 at http://bit.ly/hOgK9h Any suggestion is appreciated. Cheers Lorenzo
On 25/02/2011 8:21 AM, Lorenzo Isella wrote:> Dear All, > I need to plot some points on the surface of a sphere, but I am not sure > about how to proceed to achieve this in R (or if it is suitable for this > at all). > In any case, I am not looking for really fancy visualizations; for > instance you can consider the images between formulae 5 and 6 at > > http://bit.ly/hOgK9h > > Any suggestion is appreciated.Those plots show simple linear projections of the points, after culling those that are on the far side of the sphere. That's very easy for the points, slightly more work for the grid. I'm not aware of any package that implements all of it, but you could do it yourself fairly easily. If you want something more fancy you could use the rgl package for 3d plots that you can rotate. You'll still have to draw the grid, and you'll probably find it a little painful to implement the hidden surface removal: rgl uses depth checking to remove things, and because of rounding error it's not very good at drawing points and lines on surfaces. (There are new options to control depth checking; see "depth_mask" and "depth_test" in ?material3d. You can probably improve the default behaviour using those). Duncan Murdoch