Hi Markus, Thanks for your comments.
It still appears that v.rast.stats is giving me different values to r.univar. Essentially I'd like to clarify how the values are derived from v.rast.stats. I'm guessing that the discrepancy between my r.univar and v.rast.stats outputs relates to how I'm using g.region? The following shows my approach for deriving statistics from both r.univar and v.rast.stats. Cheers, Richard 1. Using r.univar and zones to output stats # set g.region for rasterizing vector g.region -p -a vector=BMR_bndry_epsg4326@prcp05216ijk res=0.22 projection: 3 (Latitude-Longitude) zone: 0 datum: wgs84 ellipsoid: wgs84 north: 14:31:12N south: 13:12N west: 99:39:36E east: 101:12E nsres: 0:13:12 ewres: 0:13:12 rows: 6 cols: 7 cells: 42 # rasterize vector to be used for zones v.to.rast --overwrite input=BMR_bndry_epsg4326@prcp05216ijk type=area output=BMR_bndry_epsg4326_rasterized use=cat Reading areas... Reading features... Writing raster map... Converted areas: 6 of 0 v.to.rast complete. # set g.region for zones with r.univar g.region -p rast=BMR_bndry_epsg4326_rasterized@prcp05216ijk projection: 3 (Latitude-Longitude) zone: 0 datum: wgs84 ellipsoid: wgs84 north: 14:31:12N south: 13:12N west: 99:39:36E east: 101:12E nsres: 0:13:12 ewres: 0:13:12 rows: 6 cols: 7 cells: 42 g.region -p align=cahpa_i0apr_05216_nc_remapped_nc_1@prcp05216ijk projection: 3 (Latitude-Longitude) zone: 0 datum: wgs84 ellipsoid: wgs84 north: 14:35:24N south: 13:03N west: 99:34:12E east: 101:19:48E nsres: 0:13:12 ewres: 0:13:12 rows: 7 cols: 8 cells: 56 r.univar -g -t map=cahpa_i0apr_05216_nc_remapped_nc_1@prcp05216ijk zones=BMR_bndry_epsg4326_rasterized@prcp05216ijk zone|label|non_null_cells|null_cells|min|max|range|mean|mean_of_abs|stddev|variance|coeff_var|sum|sum_abs 1|Category 1|4|0|3.58209799742326e-05|7.74326545069925e-05|4.16116745327599e-05|5.64720030524768e-05|5.64720030524768e-05|1.53324774982512e-05|2.35084866234379e-10|27.1505820043313|0.000225888012209907|0.000225888012209907 2|Category 2|2|0|3.53023679053877e-05|6.23035812168382e-05|2.70012133114506e-05|4.88029745611129e-05|4.88029745611129e-05|1.35006066557253e-05|1.82266380072614e-10|27.6634913694027|9.76059491222259e-05|9.76059491222259e-05 3|Category 3|1|0|8.14341983641498e-05|8.14341983641498e-05|0|8.14341983641498e-05|8.14341983641498e-05|0|0|0|8.14341983641498e-05|8.14341983641498e-05 4|Category 4|3|0|5.68314899282996e-05|8.2188387750648e-05|2.53568978223484e-05|6.57776896938837e-05|6.57776896938837e-05|1.16198714234862e-05|1.35021411898352e-10|17.6653687254186|0.000197333069081651|0.000197333069081651 5|Category 5|4|0|3.15697689075023e-05|4.9253627366852e-05|1.76838584593497e-05|3.7798413359269e-05|3.7798413359269e-05|7.09251495570204e-06|5.03037683968571e-11|18.7640546926894|0.000151193653437076|0.000151193653437076 6|Category 6|1|0|1.89598704309901e-05|1.89598704309901e-05|0|1.89598704309901e-05|1.89598704309901e-05|0|0|0|1.89598704309901e-05|1.89598704309901e-05 (Sun Feb 22 13:23:02 2015) Command finished (0 sec) 2. Check outputs against v.to.rast # set g.region for raster (stats to be derived from this layer): g.region -p -a raster=cahpa_i0apr_05216_nc_remapped_nc_1@prcp05216ijk res=0.22 projection: 3 (Latitude-Longitude) zone: 0 datum: wgs84 ellipsoid: wgs84 north: 35:38:24N south: 15:10:48S west: 89:45:36E east: 140:34:48E nsres: 0:13:12 ewres: 0:13:12 rows: 231 cols: 231 cells: 53361 v.rast.stats map=BMR_bndry_epsg4326@prcp05216ijk raster=cahpa_i0apr_05216_nc_remapped_nc_1@prcp05216ijk column_prefix=teststat method=number,minimum,maximum,range,average,sum Outputs from attribute table: cat,province,teststat_number,teststat_minimum,teststat_maximum,teststat_range,teststat_average,teststat_sum 1,krung_thep_maha_nakhon_bangkok,2,3.58209799742326e-05,6.23035812168382e-05,2.64826012426056e-05,4.90622805955354e-05,9.81245611910708e-05 2,samut_prakan,1,3.53023679053877e-05,3.53023679053877e-05,0,3.53023679053877e-05,3.53023679053877e-05 3,nonthaburi,2,5.02148177474737e-05,8.14341983641498e-05,3.12193806166761e-05,6.58245080558117e-05,0.000131649016111623 4,pathum_thani,3,4.46328085672576e-05,8.2188387750648e-05,3.75555791833904e-05,6.12175620820684e-05,0.000183652686246205 5,nakhon_pathom,3,3.81464305974077e-05,6.24195599812083e-05,2.42731293838006e-05,4.99398726484893e-05,0.000149819617945468 6,samut_sakhon,2,1.89598704309901e-05,7.74326545069925e-05,5.84727840760024e-05,4.81962624689913e-05,9.63925249379827e-05 -- 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-tp5188809p5189188.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
