Hi everyone, I wonder if there is a code in r that can generate a 3d convex hull from a data-frame containing 3 columns and then use another database with the same three columns and for each row determine if the xyz point is inside or not the convex hull generated with the first database? The package geometry allows to calculate a hull and it's volume. I was planning to calculate the volume of the convex hull after adding each point in the second database and if the hull gets bigger then the point is out and if not then the point is in. A problem with this method is that I have over 10 million points and the calculation for each point will take a lot of time. Any guidance will be greatly appreciated, Thanks, Camilo
Is xyz point inside 3d convex hull?
3 messages · Camilo Mora, Don McKenzie, Keith Jewell
Check the R-news archive with approrpriate keywords. There was a long exchange awhile back when I asked a similar question.
On Oct 12, 2014, at 1:20 PM, Camilo Mora <cmora at Dal.Ca> wrote:
Hi everyone, I wonder if there is a code in r that can generate a 3d convex hull from a data-frame containing 3 columns and then use another database with the same three columns and for each row determine if the xyz point is inside or not the convex hull generated with the first database? The package geometry allows to calculate a hull and it's volume. I was planning to calculate the volume of the convex hull after adding each point in the second database and if the hull gets bigger then the point is out and if not then the point is in. A problem with this method is that I have over 10 million points and the calculation for each point will take a lot of time. Any guidance will be greatly appreciated, Thanks, Camilo [[alternative HTML version deleted]]
______________________________________________ R-help at 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.
Don McKenzie Research Ecologist Pacific Wildland Fire Sciences Lab US Forest Service Affiliate Professor School of Environmental and Forest Sciences University of Washington dmck at uw.edu
Back in 2009 I posted some code to this list, see: <http://tolstoy.newcastle.edu.au/R/e8/help/09/12/8784.html> I submitted the function 'inhull' to the geometry package maintainer, but I don't think it was ever included. HTH Keith J
On 12/10/2014 21:24, Don McKenzie wrote:
Check the R-news archive with approrpriate keywords. There was a long exchange awhile back when I asked a similar question. On Oct 12, 2014, at 1:20 PM, Camilo Mora <cmora at Dal.Ca> wrote:
Hi everyone, I wonder if there is a code in r that can generate a 3d convex hull from a data-frame containing 3 columns and then use another database with the same three columns and for each row determine if the xyz point is inside or not the convex hull generated with the first database? The package geometry allows to calculate a hull and it's volume. I was planning to calculate the volume of the convex hull after adding each point in the second database and if the hull gets bigger then the point is out and if not then the point is in. A problem with this method is that I have over 10 million points and the calculation for each point will take a lot of time. Any guidance will be greatly appreciated, Thanks, Camilo [[alternative HTML version deleted]]