Actually, I think that the survey on "alpha shapes" available from:
http://www.cs.duke.edu/~edels/Surveys/
would be more closely aligned with what Michael was interested in...
url: www.econ.uiuc.edu/~roger Roger Koenker
email rkoen...@uiuc.edu Department of Economics
vox: 217-333-4558 University of Illinois
fax: 217-244-6678 Champaign, IL 61820
On Jan 20, 2009, at 6:06 PM, David Winsemius wrote:
The OP was asking whether concave hulls have been implemented. He
wasn't very helpful with his link giving the example, since it was
to the "outside" of a frame-based website. Perhaps this link (see
the bottom of that page) will be more helpful:
http://get.dsi.uminho.pt/local/results.html
It has been discussed (briefly) in r-help:
http://finzi.psych.upenn.edu/R/Rhelp02a/archive/75574.html
Some of the material in Loader's "Local Regression and Likelihood"
regarding classification looks potentially applicable.
When first I saw this question I expected that one of the r-sig-Geo
folks would have a ready answer. Perhaps a follow-up there would be
a reasonable next step?
--
David Winsemius
On Jan 20, 2009, at 6:37 PM, Charles Geyer wrote:
Message: 64
Date: Mon, 19 Jan 2009 15:14:34 -0700
From: Greg Snow <greg.s...@imail.org>
Subject: Re: [R] Concave Hull
To: Michael Kubovy <kub...@virginia.edu>, r-help
<r-help@r-project.org>
Message-ID:
<b37c0a15b8fb3c468b5bc7ebc7da14cc61c8360...@lp-exmbvs10.co.ihc.com>
Content-Type: text/plain; charset="us-ascii"
I don't know if it is the same algorithm or not, but there is the
function "chull" that finds the convex hull.
Also the R function "redundant" in the contributed package "rcdd"
efficiently
finds convex hulls in d-dimensional space for arbitrary d (chull
only does
d = 2). See Sections 4.2 and 5.2 of the rcdd package vignette.
Hope this helps,
--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.s...@imail.org
801.408.8111
-----Original Message-----
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-
project.org] On Behalf Of Michael Kubovy
Sent: Saturday, January 17, 2009 9:49 AM
To: r-help
Subject: [R] Concave Hull
Dear Friends,
Here is an algorithm for finding concave hulls:
http://get.dsi.uminho.pt/local/
Has anyone implemented such an algorithm in R?
RSiteSearch('concave hull') didn't reveal one (I think).
_____________________________
Professor Michael Kubovy
University of Virginia
Department of Psychology
Postal Address:
P.O.Box 400400, Charlottesville, VA 22904-4400
Express Parcels Address:
Gilmer Hall, Room 102, McCormick Road, Charlottesville, VA 22903
Office: B011; Phone: +1-434-982-4729
Lab: B019; Phone: +1-434-982-4751
WWW: http://www.people.virginia.edu/~mk9y/
Skype name: polyurinsane
[[alternative HTML version deleted]]
______________________________________________
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.
______________________________________________
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.
