[GRASS-user] r.covar vs layerStats in R

[Markus Neteler]

On Sun, Nov 18, 2018 at 10:32 PM Micha Silver <tsvibar at gmail.com> wrote:
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> I am preparing a correlation matrix for 7 raster layers. The results using the r.covar module are different from the R layerStats function. I suspect this is due to handling of null cells. The R function has a parameter to remove NA cells, but the GRASS module, I think, just loops over all cells, including no value.
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> Can anyone confirm that GRASS does not deal with null cells, and that this would cause the difference in correlation results?

Here how r.covar treats NULL cells:

https://trac.osgeo.org/grass/browser/grass/trunk/raster/r.covar/main.c#L93

Markus