Oops, there's a mistake in the first line of code. should be: extract(raster, SPdataframe,fun="mean",na.rm=TRUE,method="simple")
On 17.02.2012, at 17:58, Emmenegger Tamara wrote:
Merci! -----Urspr?ngliche Nachricht----- Von: Rafael W?est [mailto:rafael.wueest at wsl.ch] Gesendet: Freitag, 17. Februar 2012 17:45 An: Emmenegger Tamara Betreff: Re: [R-sig-Geo] Polygons of a SpatialPolygonsDataFrame Hi Tamara assuming SPdatframe is the SpatialPolygonsDataFrame, if you need the mean of every polygon, then you can as well try extract(raster, SpatialPolygons(SPdataframe at polygons),fun="mean",na.rm=TRUE,method="simple") this will give you the mean for each polygon in a vector. If you want to do them seperately, you will have to select each polygon like: extract(raster, SPdataframe[i,],fun="mean",na.rm=TRUE,method="simple") Rafael On 17.02.2012, at 16:57, Emmenegger Tamara wrote:
I have a SpatialPolygonsDataFrame with 120 Polygons and some associated data. Now I'd like to extract the mean of the values on a raster within each polygon separately. I succeded in plotting individual polygons with: plot(SpatialPolygons(SPdataframe at polygons)[i]) But it did not work to extract the values in the same manner: extract(raster, SpatialPolygons(SPdataframe at polygons)[i],fun="mean",na.rm=TRUE,method= "simple") Can anyone explain the difference between the use of the same indexation in this two cases? What is the official way to choose particular polygons of a SpatialPolygonsData- Frame with indices? Thank you a lot for your help in advance!
____________________________________________________ Tamara Emmenegger Msc student Bird migration Tel. ++41 41 462 97 00 tamara.emmenegger at vogelwarte.ch<mailto:tamara.emmenegger at vogelwarte.ch www.vogelwarte.ch<http://www.vogelwarte.ch/> Schweizerische Vogelwarte | Seerose 1 | CH-6204 Sempach | Schweiz Station ornithologique suisse | Seerose 1 | CH-6204 Sempach | Suisse Stazione ornitologica svizzera | Seerose 1 | CH-6204 Sempach | Svizzera Swiss Ornithological Institute | Seerose 1 | CH-6204 Sempach | Switzerland [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo
-- Rafael W?est Swiss Federal Research Institute WSL Z?rcherstrasse 111 8903 Birmensdorf Switzerland +41 44 7392126 rafael.wueest at wsl.ch http://www.wsl.ch/info/mitarbeitende/wueest
-- Rafael W?est Swiss Federal Research Institute WSL Z?rcherstrasse 111 8903 Birmensdorf Switzerland +41 44 7392126 rafael.wueest at wsl.ch http://www.wsl.ch/info/mitarbeitende/wueest