Hi Mike, Thanks for that suggestion, It had not occurred to me to overload as.matrix. Done that now (raster version 1.6-7) such that as.matrix(projras) works.
Best, Robert On Wed, Oct 27, 2010 at 4:01 PM, Michael Sumner <mdsum...@gmail.com> wrote: > Thanks Robert, I still haven't explored raster enough. > > I tried as.matrix(projras) - have you considered adding methods like > this? I'm afraid I still don't know the structure of the raster data > sets enough to know if that makes sense, but I think sp returns > another orientation in this way: > > as.matrix(spprojras) > > > Cheers, Mike. > > On Thu, Oct 28, 2010 at 9:54 AM, Robert J. Hijmans <r.hijm...@gmail.com> > wrote: >> After this: >> >>> projras <- projectRaster(r0, pr) >> >> You could also do plot(projras) or image(projras) and >> >> v <- getValues(projras, format='matrix') >> >> To get a matrix of values, with the advantage that values in this >> matrix are organized as on the map (probably what you would expect), >> which is different in matrix 'm' in Mike's example. >> >> Robert >> >> On Wed, Oct 27, 2010 at 2:16 PM, Michael Sumner <mdsum...@gmail.com> wrote: >>> This is a dummy example - especially in terms of made up coordinate >>> system details, but shows how you can reproject with the raster >>> package: >>> >>> library(rgdal) >>> >>> ## create a grid, with dummy coordinates / projection >>> >>> im <- image2Grid(list(x = 1e5 * (1:nrow(volcano)), y = 1e5 * >>> (1:ncol(volcano)), z = volcano), p4 = "+proj=laea") >>> >>> writeGDAL(im, "dummy.tif") >>> >>> ## now the process, using raster package >>> >>> library(raster) >>> >>> >>> r0 <- raster("dummy.tif") >>> >>> # proj.4 projection description >>> newproj <- "+proj=longlat +ellps=WGS84" >>> >>> pr <- projectExtent(r0, newproj) >>> ## (optionally) Adjust the cell size >>> ## res(pr) <- res(pr)/2 >>> >>> >>> # project the values of RasterLayer 'r' to the new RasterLayer 'projras' >>> projras <- projectRaster(r0, pr) >>> >>> ## now go back to sp and extract matrix >>> >>> spprojras <- as(projras, "SpatialGridDataFrame") >>> >>> m <- as.image.SpatialGridDataFrame(spprojras)$z >>> >>> image(m) >>> >>> >>> I'm not sure if the coercion to SpatialGridDataFrame will >>> automatically give you all of the detail in the source by default for >>> large grids, but there would be a way. >>> >>> Cheers, MIke. >>> On Wed, Oct 27, 2010 at 7:03 PM, <fsan...@ujaen.es> wrote: >>>> Dear R community, >>>> >>>> I'm sorry, but I am newbie with GIS. I have to import a tiff using a >>>> geotiff tool, and convert it into a data matrix. The initial projection is >>>> Lambert Azimuthal Equal Area, and I would like to get the final matrix in >>>> a regular lat/lon grid. >>>> >>>> It is possible to do it with R? >>>> >>>> Thanks in advance. >>>> >>>> _______________________________________________ >>>> R-sig-Geo mailing list >>>> R-sig-Geo@stat.math.ethz.ch >>>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo >>>> >>> >>> >>> >>> -- >>> Michael Sumner >>> Institute for Marine and Antarctic Studies, University of Tasmania >>> Hobart, Australia >>> e-mail: mdsum...@gmail.com >>> >>> _______________________________________________ >>> 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 >> > > > > -- > Michael Sumner > Institute for Marine and Antarctic Studies, University of Tasmania > Hobart, Australia > e-mail: mdsum...@gmail.com > _______________________________________________ R-sig-Geo mailing list R-sig-Geo@stat.math.ethz.ch https://stat.ethz.ch/mailman/listinfo/r-sig-geo