Hi, I'm trying to determine the specifics of how v.rast.stats calculates means and other statistics, for which I have a couple of queries.
I apologise in advance if this information exists online, but I couldn't find all the details in module guidelines or related documents and scripts. I understand that v.rast.stats uses v.to.rast and r.univar for determining means and statistics. Qu. 1. Raster cells are only created (by v.to.rast) if their centre point is within the area boundary ? I'm using a vector area layer, and my observation after rasterizing, is that this is the case, and cells are not created if their centre point lies outside the area boundary. Qu. 2. If a single cell representing a unique category in the zones layer (generated previously by v.to.rast) overlays four cells in the input raster, how is the mean calculated. Is it a simple sum of the four cell values divided by n number of cells (four in this case), or is the value weighted in some way? Not being a expert programmer, I can't really tell from the r.univar script, and it doesn't appear from my observation to be a simple mean calculation. Many thanks for your comments, Richard GRASS version: 7.0.0svn GRASS SVN Revision: 64042 Build Date: 2015-01-10 Build Platform: i686-pc-linux-gnu GDAL/OGR: 1.11.1 PROJ.4: 4.9.0 GEOS: 3.4.2 SQLite: 3.7.9 Python: 2.7.3 wxPython: 2.8.12.1 Platform: Linux-3.2.0-31-generic-pae-i686-with-LinuxMint-13-maya -- View this message in context: http://osgeo-org.1560.x6.nabble.com/Searching-for-technical-details-on-how-v-rast-stats-calculates-means-and-other-statistics-tp5188809.html Sent from the Grass - Users mailing list archive at Nabble.com. _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
