Agustin, PostGIS WKT Raster was made to do exactly this kind of operation on large datasets. Give it a try!
http://trac.osgeo.org/postgis/wiki/WKTRasterTutorial01 Pierre >-----Original Message----- >From: r-sig-geo-boun...@stat.math.ethz.ch >[mailto:r-sig-geo-boun...@stat.math.ethz.ch] On Behalf Of >Agustin Lobo >Sent: 30 juin 2010 10:13 >To: r-sig-geo >Cc: agustin.l...@ija.csic.es >Subject: [R-sig-Geo] polygonValues (raster): Very slow > >Hi! >I'm trying: > >> eugrd025EFDC <- readOGR(dsn="eugrd025EFDC",layer="eugrd025EFDC") >v <- polygonValues(p=eugrd025EFDC, Br, weights=TRUE) > >where > >> str(eugrd025EFDC,max.level=2) >Formal class 'SpatialPolygonsDataFrame' [package "sp"] with 5 slots > ..@ data :'data.frame': 18000 obs. of 5 variables: > ..@ polygons :List of 18000 > .. .. [list output truncated] > ..@ plotOrder : int [1:18000] 17901 17900 17902 17903 17899 17898 >17904 17897 17905 17906 ... > ..@ bbox : num [1:2, 1:2] 2484331 1314148 6575852 4328780 > .. ..- attr(*, "dimnames")=List of 2 > ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots > >> summary(Br) >Cells: 13967442 >NAs : 0 > > >Min. 0.00 >1st Qu. 0.00 >Median 0.00 >Mean 48.82 >3rd Qu. 0.00 >Max. 4999.00 > >so quite large objects. > >The problem is that polygonValues() has been running (and not >completed the task) for >more than 2 h on a intel core i7 machine with 16 Gb RAM (Dell >Precision M6500), so a pretty powerful machine. >Is there any way I could speed up this process? >Also, is there anything I could do in order to take better advantage >of the 8 processing threads? >Currently, I see only 1 cpu working for R processes and the rest >remain pretty inactive > >Thanks > >Agus > >_______________________________________________ >R-sig-Geo mailing list >R-sig-Geo@stat.math.ethz.ch >https://stat.ethz.ch/mailman/listinfo/r-sig-geo _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo
