GWR with GWT file
On Thu, 11 Mar 2010, Jay Douillard wrote:
I'm working on a project where the distance between two polygons may be a poor measure of connectivity(contigious polygons that may have an impassible mountain chain between them. To get a better measure of distance I've used road network distances from population weighted centroids of the polygons. I've created a row standarized gwt style file using arcgis's network tools, and a bit of table editing. I can successfully import this into R. File format in "old style GWT" for example:
473 1 2 .111 1 3 .22 1 4 .66 2 1 .11 Is possible to use your own weighting scheme in spgwr? Is it using a listw object? I couldn't find any indication in the documentation.
Jay, It isn't, but it probably wouldn't be too hard to do under certain conditions. The non-neighbours would be treated as outside the bandwidth, I suppose, otherwise one is looking at a full matrix for asymmetric road networks. The source for spgwr is on the r-spatial project on sourceforge, so you could check out what there is and see how one might add a listw= argument to gwr() for a given bandwidth first - branching around the spDistsN1() in .GWR_int() after passing the listw object through. Roger
thanks! ---- Jay Douillard Geospatial Technical Lead 604.827.4401 Human Early Learning Partnership www.earlylearning.ubc.ca
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Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Helleveien 30, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43 e-mail: Roger.Bivand at nhh.no