Dominik, If you want to deal with bigger data sets in a fast and more flexible way I strongly suggest to use GRASS7. Rgrass7 provides a very good "r-ish" wrapper to use it from R. If You are interested i 'll post a typical setup and example for your question. Please note you need obligatory a GRASS 7 installation on your system.
Cheers Chris Am 19. Februar 2016 16:55:32 MEZ, schrieb Dominik Schneider <dominik.schnei...@colorado.edu>: >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 -- Diese Nachricht wurde von meinem Android-Mobiltelefon mit K-9 Mail gesendet. [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
