Determine angle between polyline segments
Hello, Have you considered using the 'adehabitat' package? It presents classes and tools for the analysis of trajectories, and automagically computes absolute and relative angles. I'm not that familiar with polylines (in ArcGIS or sp) so that I don't have a working example at hand, but you'd have to extract coordinates of the polylines to build a ltraj object (using as.ltraj), keeping the ID of the line as the ID of the ltraj, and with 'typeII = FALSE' which means that you don't have the exact date. In the end, an object of class ltraj is a list with a data frame for each element of the list (for you a line), which gives you both kind of angles among other variables (dx, dy, dist, etc.). Hope this helps, Mathieu. Le 30/07/2010 03:33, Rainer M Krug a ?crit :
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi a friend of mine wants (needs?) to determine the angle between segments in an ESRI polyline (line vector feature). As there does not seem to be an easy way in ArcGIS 9.2, I thought about askeng here: Is there way of calculating these angles between the different line segments in R (after importing the line feature into R)? Thanks, Rainer - -- Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys. (Germany) Centre of Excellence for Invasion Biology Natural Sciences Building Office Suite 2039 Stellenbosch University Main Campus, Merriman Avenue Stellenbosch South Africa Tel: +33 - (0)9 53 10 27 44 Cell: +27 - (0)8 39 47 90 42 Fax (SA): +27 - (0)8 65 16 27 82 Fax (D) : +49 - (0)3 21 21 25 22 44 Fax (FR): +33 - (0)9 58 10 27 44 email: Rainer at krugs.de Skype: RMkrug -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkxSgFYACgkQoYgNqgF2egp34ACeMiVR1XG9xb/YH7KpFJ+3jTln 5WUAn3Cxbl1BCr9iSidDFYcmwdiiYhFh =P2Jq -----END PGP SIGNATURE-----
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~$ whoami Mathieu Basille, Post-Doc ~$ locate Laboratoire d'?cologie Comportementale et de Conservation de la Faune + Centre d'?tude de la For?t D?partement de Biologie Universit? Laval, Qu?bec ~$ info http://ase-research.org/basille ~$ fortune ``If you can't win by reason, go for volume.'' Calvin, by Bill Watterson.