On Mon, 15 Dec 2008, Rawlins, Barry G wrote:
I would like to calculate a moving window variance across a large, irregular spatial dataset (1.1 million points) - I have looked for various functions but have not been able to find one that will do this.
How irregular? Is the moving window adaptive (k nearest neighbours) or fixed in distance for a given bandwidth - hence widely varying counts of points within the window? Do you need the moving window variances for the same support (points) as the data, or for different points (maybe a grid)? Could the task be divided up into (overlapping) tiles if memory is a major constraint? If k nearest neighbours, ANN (approximate nearest neighbours) has been ported several times to R, but not generalised - I can make one off-CRAN version available if need be. This thread may be relevant:
https://stat.ethz.ch/pipermail/r-sig-geo/2008-December/004644.html Roger
Any suggestions much appreciated. Barry R
-- 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: [email protected] _______________________________________________ R-sig-Geo mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-geo
