In Grass maybe you could use the boundaries instead of the areas. The distances would be between the boundaries' linestrings instead of centroids.
giovanni 2012/5/7 Roger Bivand <[email protected]> > On Mon, 7 May 2012, Rainer M Krug wrote: > > -----BEGIN PGP SIGNED MESSAGE----- >> Hash: SHA1 >> >> Hi >> >> I have the following (presumibly simple?) question: >> >> I have a certain number of patches (islands) in a landscape of which I >> need to know the nearest neighbour distance. As the problem is related to >> dispersal, I would need to know the actual shortest distance between the >> actual polygons and not only the centroids. Is there an easy way to obtain >> these in R or in GRASS? I am only aware of nearest neighbour distance >> between points. >> > > In R, if the coordinates are projected, use gDistance(..., byid=TRUE) in > the rgeos package to get a matrix in the metric of the projection. If not > projected, project if possible. > > I don't think that the geosphere package provides for the unprojected case. > > Roger > > > >> Thanks, >> >> Rainer >> >> >> - -- >> Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation >> Biology, UCT), Dipl. Phys. >> (Germany) >> >> Centre of Excellence for Invasion Biology >> Stellenbosch University >> South Africa >> >> Tel : +33 - (0)9 53 10 27 44 >> Cell: +33 - (0)6 85 62 59 98 >> Fax : +33 - (0)9 58 10 27 44 >> >> Fax (D): +49 - (0)3 21 21 25 22 44 >> >> email: [email protected] >> >> Skype: RMkrug >> -----BEGIN PGP SIGNATURE----- >> Version: GnuPG v1.4.11 (GNU/Linux) >> Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ >> >> iEYEARECAAYFAk+**nux4ACgkQoYgNqgF2egqaDgCeKx1Bk**rDsn+NldthK1GzFVYWp >> stwAnRz+uj47cBMNid/**QPdIRXwAnVs/8 >> =yBff >> -----END PGP SIGNATURE----- >> ______________________________**_________________ >> grass-stats mailing list >> [email protected] >> http://lists.osgeo.org/**mailman/listinfo/grass-stats<http://lists.osgeo.org/mailman/listinfo/grass-stats> >> >> > -- > Roger Bivand > Department of Economics, NHH Norwegian School of Economics, > Helleveien 30, N-5045 Bergen, Norway. > voice: +47 55 95 93 55; fax +47 55 95 95 43 > e-mail: [email protected] > > > ______________________________**_________________ > grass-stats mailing list > [email protected] > http://lists.osgeo.org/**mailman/listinfo/grass-stats<http://lists.osgeo.org/mailman/listinfo/grass-stats> >
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