Renaud, Here another way: library(raster) r <- raster(sgdf1, 1) ra <- aggregate(r, 10, mean) sgdf3 <- as(ra, 'SpatialGridDataFrame')
> values(ra) [1] 0.43 0.45 0.57 0.50 0.49 0.47 0.58 0.50 0.61 0.49 0.49 0.53 0.54 0.51 0.53 0.42 0.48 0.51 0.54 0.53 0.50 [22] 0.52 0.39 0.52 0.52 0.62 0.53 0.48 0.52 0.48 0.52 0.45 0.50 0.48 0.43 0.47 0.52 0.49 0.43 0.59 0.54 0.52 [43] 0.53 0.53 0.48 0.57 0.46 0.54 0.49 0.48 0.47 0.48 0.47 0.50 0.48 0.49 0.47 0.45 0.50 0.52 0.54 0.46 0.49 [64] 0.52 0.54 0.50 0.46 0.43 0.49 0.46 0.55 0.52 0.52 0.47 0.41 0.51 0.56 0.40 0.56 0.50 0.47 0.48 0.55 0.44 [85] 0.57 0.44 0.51 0.49 0.50 0.49 0.56 0.54 0.46 0.50 0.52 0.49 0.52 0.42 0.57 0.54 > Robert On Tue, Dec 22, 2009 at 1:36 AM, Renaud Lancelot <renaud.lance...@cirad.fr> wrote: > Dear all, > > I have two "nested" grids (SpatialGridDataFrame) looking like this: > > prj <- "+proj=utm +zone=28 +ellps=WGS84 +datum=WGS84 +units=m +no_defs" > gt1 <- GridTopology(c(5, 5), c(10, 10), c(100, 100)) > gt2 <- GridTopology(c(50, 50), c(100, 100), c(10, 10)) > band1 <- sample(c(0, 1), replace = TRUE, size = 10000) > sgdf1 <- SpatialGridDataFrame(gt1, data.frame(band1), CRS(prj)) > sgdf2 <- SpatialGridDataFrame(gt2, data.frame(band1=rep(0, 100)), CRS(prj)) > ## Graphic display > spplot(sgdf1, scales = list(draw = TRUE), > panel = function(...){ > panel.gridplot(...) > sp.grid(sgdf2, col = 0) > }) > > I want to compute the mean (and other statistics) of sg...@data$band1 > according to the cells defined in sgdf2. How can I do that ? I tried to use > overlay, without success: > >> sgdf3 <- overlay(sgdf1, sgdf2, fn = mean) >> sg...@data$band1 > [1] 1 0 0 0 0 0 1 1 1 0 0 1 0 0 0 0 0 1 1 0 1 0 1 1 0 1 0 0 0 0 > [31] 0 0 1 0 1 1 1 0 0 0 0 0 0 1 0 1 1 0 0 0 1 0 1 0 1 0 1 1 0 0 > [61] 1 1 0 1 1 1 1 0 0 0 1 1 0 0 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 > [91] 1 0 1 1 1 0 1 0 1 0 > > All the best, > > Renaud > > > > -- > Renaud Lancelot > EDEN Project, coordinator > http://www.eden-fp6project.net/ > << EDEN International Conference, Montpellier, 10-12 May 2010 >> > << http://international-conference2010.eden-fp6project.net/ >> > > UMR CIRAD-INRA "Contrôle des maladies animales exotiques et émergentes" > Joint research unit "Control of emerging and exotic animal diseases" > > CIRAD, Campus International de Baillarguet TA A-DIR / B > F34398 Montpellier > http://www.cirad.fr http://bluetongue.cirad.fr/ > > Tel. +33 4 67 59 37 17 - Fax +33 4 67 59 37 95 > Secr. +33 4 67 59 37 37 - Cell. +33 6 77 52 08 69 > > _______________________________________________ > 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