Roger, Thanks for your reference. Since I can get the polygon coordinates (and have the coordinates of my sites, I can cobble together a function that will do the trick.
Again, thanks, Clint On Fri, 2 Apr 2004, Roger Bivand wrote: > On Fri, 2 Apr 2004, Clint Bowman wrote: > > > I have shapefiles for the state climatic divisions for the United States > > and read.shape brings them in wonderfully. Now I wish to run through a > > list of several thousand observation sites to find out in which division > > each is located. I figure that I can compute the winding number for each > > site and be done. However a search doesn't find any references and I > > can't find a winding number function among the map/tools/stats. I have > > the code for an efficient C++ but was expecting that it would already be > > implemented as an R function > > > > Since I haven't used the map/tools/stats collection before, I suspect I'm > > overlooking the function and would be thankful for a pointer. > > > > This is work in progress - where all good ideas and contributions will be > welcome. If you look on http://sourceforge.net/projects/r-spatial/, you > will see an "alpha" package called "sp", which already has a > point-in-polygon facility, but which may not scale up to the kinds of data > volumes you have, but which invites a spatial query (match polygon?) > function between a SpatialDataFrame with point coordinates and a > SpatialDataPolygons object (sometime). This is only as source packages so > far, so Windows binaries are not yet available. > > I have used the splancs package inout() function before, trying the points > coordinate matrix on each polygon in turn; splancs is available as a > Windows binary. This ought to be less "rough at the edges", and in time > will be. The immediate solution is to use splancs, but this will not work > if the Shapes have multiple polygons. There is a more specialised list for > these kinds of questions in addition to r-help: > > https://www.stat.math.ethz.ch/mailman/listinfo/r-sig-geo > > and since yesterday (thanks to Jonathan Baron), its archives are also > searchable from: > > http://finzi.psych.upenn.edu/search.html > > This question hasn't come up there, but maybe we could move further > discussion there - posting only for subscribers? > > > TIA > > > > Clint > > > > > > -- Clint Bowman INTERNET: [EMAIL PROTECTED] Air Quality Modeler INTERNET: [EMAIL PROTECTED] Department of Ecology VOICE: (360) 407-6815 PO Box 47600 FAX: (360) 407-7534 Olympia, WA 98504-7600 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
