Chris, Actually I take that back, using extract() with `weights=TRUE` returned `0` instead of NA values for these problematic coastal admin units. Think I might have to impute them manually.
--Mel. On 10/18/2016 2:33 PM, Bacou, Melanie wrote: > > Chris, > Thanks, using `weights=TRUE` to compute the means fixed the problem. > Perfect, --Mel. > > > On 10/18/2016 11:10 AM, chris english wrote: >> >> Mel, >> >> Looking at detail in cjg.png the northmost missing data island shows >> approx 20-25 in Southern three quarters and 0-5 the small North at >> tip of island. Directly above this 0-5 another coastal 0-5. >> If a substantial east-west scarp bisected the island it might >> explain. I would otherwise expect a very slight mismatch in >> projection, a thing I often have problems with. >> >> Though reading raster::extract it looks like you want to employ the >> weights are if your polys are relatively smaller than your cells. >> >> HTH >> Chris >> >> >> On Oct 18, 2016 4:35 PM, "Bacou, Melanie" <m...@mbacou.com >> <mailto:m...@mbacou.com>> wrote: >> >> Hi, >> I'm summarizing biophysical rasters (UDEL precipitation and >> temperature) across administrative units for countries in Africa >> using (pseudo code): >> >> raster::extract(udel, admin, fun=mean, na.rm=T, small=T) >> >> Out of the 756 units I need data for, extract() fails to return >> means for a few coastal units (in red on the maps below) even >> though the rasters show data at these locations. >> >> Is there a particular reason why this might happen? Shall I look >> for possible geometry errors in my source shapefiles, or could >> there be another reason? >> >> Maps here: >> https://dl.dropboxusercontent.com/u/30925475/eclgcdmhapfplaml.png >> <https://dl.dropboxusercontent.com/u/30925475/eclgcdmhapfplaml.png> >> https://dl.dropboxusercontent.com/u/30925475/lmkgmdoohpmhdcjg.png >> <https://dl.dropboxusercontent.com/u/30925475/lmkgmdoohpmhdcjg.png> >> >> Thanks for any tip. --Mel. >> >> _______________________________________________ >> R-sig-Geo mailing list >> R-sig-Geo@r-project.org <mailto:R-sig-Geo@r-project.org> >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo >> <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
