[R] Visualizing Points on a Sphere
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 __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Visualizing Points on a Sphere
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 __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Visualizing Points on a Sphere
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 __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
