I think I discovered the problem. This was a mistake on my side:
The summary() function in R applied on a raster does subsample the
data in case of very large raster maps. However, this seems to
cause that summary information about NA gets lost and no NA are
mentioned in the summary output
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
You probably have good reasons for your work flow, but just to make sure:
is there a specific reason to export to geotiff first? It seems easier to
import the raster layer directly from GRASS into R using the spgrass6
package (readRAST6)? You can subsequently convert the spatial raster to the
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
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
Hello!
Did you try this one?
*r.out.gdal etc nodata*=*'NA'*
On 4 September 2014 14:27, Johannes Radinger johannesradin...@gmail.com
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
On Thu, Sep 4, 2014 at 3:38 PM, Nuno Sá nunocesard...@gmail.com wrote:
Hello!
Did you try this one?
*r.out.gdal etc nodata*=*'NA'*
As mentioned in the manual of r.out.gdal, the no data parameter takes only
float values
and no strings like 'NA'. Without stating as specific value in GRASS,
Ok, didn't check that before since I didn't have the same problem before.
Try exporting with a crazy value as NA such as in a 16bit unsigned
r.out.gdal etc nodata=65535
Then on R use the mask function such as:
mask(x, mask, filename=, inverse=FALSE, maskvalue=65535,
updatevalue='NA', ...)
