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On 19/11/2018 12:41, Markus Neteler
wrote:
Hi MarkusOn Sun, Nov 18, 2018 at 10:32 PM Micha Silver <tsvi...@gmail.com> wrote: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.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 Thanks, I missed those lines when I glanced over the source (not a C programmer). I'll do some more testing to try to understand why I'm getting different results from R compared to GRASS. Markus -- Micha Silver Ben Gurion Univ. Sde Boker, Remote Sensing Lab +972-523-665918 |
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