There is a package on CRAN implementing such an idea: alphahull, phull is other package,
kjetil On Thu, Nov 26, 2009 at 6:11 PM, baptiste auguie <baptiste.aug...@googlemail.com> wrote: > 2009/11/26 Ted Harding <ted.hard...@manchester.ac.uk>: >> Raising a rather general question here. >> >> This is a tantalising discussion, but the notion of "concave hull" >> strikes me as extremely ill-defined! >> >> I'd like to see statement of what it is (generically) supposed to be. > > I'm curious too, but I can imagine the following definition, > > Consider a sphere (n-dimensional maybe) that we let come in contact > with the scatter of points from outside. The set of points that the > sphere can attain may define unambiguously (I think) a concave hull, > for a specified sphere radius. The convex hull is obtained in the > limit of infinite radius (plane). > > It's probably not exactly this, but I guess that's the rough idea. > > Just a thought, > > baptiste > > ______________________________________________ > 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.
