Hello! Did you try this one?
*r.out.gdal etc nodata*=*'NA'* On 4 September 2014 14:27, Johannes Radinger <[email protected]> wrote: > Hi all, > > of course it is possible to load the raster maps directly via spgrass6. > However, we use this work > flow also to exchange some of the maps between different users (e.g. via > email) and to permanently > store single files (geotiffs that contain the proj information within the > file). So, I agree that using spgrass6 would be much more efficient, but > I'll stick to exporting to geotiffs and so I need to solve the issues with > NA's. > > /Johannes > > > On Thu, Sep 4, 2014 at 2:31 PM, Thomas Adams <[email protected]> wrote: > >> Johannes, >> >> If you want to read your file into R, there is no need to export your map >> from GRASS to do this. Simply install and use the R contributed package >> 'spgrass6' (spgrass6 has R dependencies that need to be installed first); >> it works wonderfully: >> >> Within GRASS, at the GRASS terminal prompt... >> >> > library(spgrass6) >> Loading required package: sp >> Loading required package: XML >> GRASS GIS interface loaded with GRASS version: GRASS 7.0.0beta3 (2014) >> and location: ohrfc_mpe >> > dat<-readRAST6("xmrg0101200306z") >> > image(dat) >> >> This is far more efficient. >> >> Tom >> >> >> On Thu, Sep 4, 2014 at 5:32 AM, Johannes Radinger < >> [email protected]> wrote: >> >>> Hi, >>> >>> I want to export a raster map (FCELL) from GRASS70 to the geotiff format >>> using r.out.gdal and to import it later on in R. The map contains many no >>> data values. >>> >>> Here some details about the raster: >>> Type of Map: raster Number of Categories: 0 >>> Data Type: FCELL >>> Rows: 750 >>> Columns: 750 >>> Total Cells: 562500 >>> total null and non-null cells: 15105636 >>> total null cells: 15105047 >>> >>> So when I export the map, r.out.gdal reports: "Input raster map contains >>> cells with NULL-value (no-data). The value -nan will be used to represent >>> no-data values in the input map. You can specify a nodata value with the >>> nodata option." >>> >>> When I subsequently try to import the geotiff into R (using the package >>> 'Raster') the nodata values are not recognised as NA's: >>> >>> a <- raster("*.tif") >>> summary(a) >>> Min. 0.5294496 >>> 1st Qu. 0.7171210 >>> Median 0.7871540 >>> 3rd Qu. 1.1581826 >>> Max. 1.5494517 >>> NA's 0.0000000 >>> >>> So I am wondering if I need to set any specific parameter during the >>> export (r.out.gdal) or import (raster()). >>> >>> As I am not only exporting FCELL (Float32) raster but also multiple >>> (N=500) other rasters to R I would be interested in a solution also for >>> DCELL (Float64). Of course I can export all of as Float64 as the file size >>> should not be a problem. >>> >>> Any suggestions or experiences of handling NA's during raster exchange >>> between GRASS and R? >>> >>> /Johannes >>> >>> _______________________________________________ >>> grass-user mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/grass-user >>> >> >> >> >> > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user > -- Nuno César de Sá +351 91 961 90 37
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