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
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