Thanks for the suggestion Chris. I'm familiar with gdaldem, which raster::terrain is based on, to compute slope from a dem. I now realize that my example isnt a good one because neighbors=8 would achieve what I described. However I actually want some flexibility such that I can specifiy neighbors=16 so that it uses the next "ring" of cells.
I played around with focal() with weight argument = matrix(rep(c(1,0,0,0,1),5),byrow=T) but couldn't figure out how to solve for a directional slope. On Fri, Feb 19, 2016 at 4:09 AM, chris english < englishchristoph...@gmail.com> wrote: > Dominik, > > r <- raster(nrows=22, ncols=20, xmn=-58, xmx=-48, ymn=-33, ymx=-22) > vals <- sample.int(1e3,440) > r[ ] <- vals > #raster::terrain > terr_r <- terrain(r, opt='slope', unit='degrees', neighbors=8) > Ah, but it appears you want up sampling to 1.5 degrees rather than 0.5 deg. > so maybe spatial.tools::projectRaster_rigorous then raster:terrain. > > I'm inclined to end that last so maybe with a question mark. Sorry for an > essentially inconclusive response but I was happy to find terrain in any > case. > Chris > > On Fri, Feb 19, 2016 at 2:59 AM, Dominik Schneider < > dominik.schnei...@colorado.edu> wrote: > >> I need to calculate slope at different scales. In the case below, r is a >> 0.5deg resolution raster and I want the slope for 1.5 deg centered on each >> of those 0.5 deg pixels. I'm trying to estimate which side of mountain >> range each pixel is on. So the resulting raster would have the same number >> of pixels as r. The edges can be NA. >> any suggestions would be appreciated. Thanks >> >> >> r <- raster(nrows=22, ncols=20, xmn=-58, xmx=-48, ymn=-33, ymx=-22) >> setValues(r,rnorm(440)) >> >> [[alternative HTML version deleted]] >> >> _______________________________________________ >> R-sig-Geo mailing list >> R-sig-Geo@r-project.org >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo >> > > [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo