Dear list, I am processing gridded data like DEMs, imported in R from geotiff files. Of course, such data is regularly gridded, but very often with NA values. In the framwork of some tests, I have to generate a neighbourhood of the DEM, so that to extract local extrema of the layer. For this task, I wrote a function based on the knearneig() function from the spdep package, with k=4 or k=8, to generate and analyse the neighbourhood of each point.
Unfortunately, I often have to process big datasets (let's say grids with between 50,000 and 350,000 points), and that's working but knearneigh() takes *hours* to process. Does anybody would have any suggestion to improve the efficiency of this step ? Thanks, Pierre _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo