[GRASS-user] Searching for technical details on how v.rast.stats calculates means and other statistics

[RichardCooper]

I seem to be getting an error with r.univar when using a zone file.

I run, g.region as follows:
g.region -a raster=cahpa_i0apr_05216_nc_remapped_nc_1 at prcp05216ijk res=0.22   

Then r.univar (see below).
There are 6 categories in the zone file, but r.univar reports null cells for
category 1? Initially I thought it was me not setting g.region correctly,
but I can't seem to get it to work as expected.

Any ideas would be welcome.

Cheers,
Richard

r.univar map=cahpa_i0apr_05216_nc_remapped_nc_1 at prcp05216ijk
zones=BMR_bndry_epsg4326_rasterized at prcp05216ijk
zone 1 Category 1
total null and non-null cells: 4
total null cells: 0
Of the non-null cells:
----------------------
n: 4
minimum: 3.5821e-05
maximum: 7.74327e-05
range: 4.16117e-05
mean: 5.6472e-05
mean of absolute values: 5.6472e-05
standard deviation: 1.53325e-05
variance: 2.35085e-10
variation coefficient: 27.1506 %
sum: 0.000225888012209907
zone 2 Category 2
total null and non-null cells: 2
total null cells: 0
Of the non-null cells:
----------------------
n: 2
minimum: 3.53024e-05
maximum: 6.23036e-05
range: 2.70012e-05
mean: 4.8803e-05
mean of absolute values: 4.8803e-05
standard deviation: 1.35006e-05
variance: 1.82266e-10
variation coefficient: 27.6635 %
sum: 9.76059491222259e-05
zone 3 Category 3
total null and non-null cells: 1
total null cells: 0
Of the non-null cells:
----------------------
n: 1
minimum: 8.14342e-05
maximum: 8.14342e-05
range: 0
mean: 8.14342e-05
mean of absolute values: 8.14342e-05
standard deviation: 0
variance: 0
variation coefficient: 0 %
sum: 8.14341983641498e-05
zone 4 Category 4
total null and non-null cells: 3
total null cells: 0
Of the non-null cells:
----------------------


This is my zones file:
Type of Map:  raster               Number of Categories: 6               
 |   Data Type:    CELL                                                       
 |   Rows:         231                                                        
 |   Columns:      231                                                        
 |   Total Cells:  53361                                                      
 |        Projection: Latitude-Longitude                                      
 |            N:  35:38:24N    S:  15:10:48S   Res: 0:13:12                   
 |            E: 140:34:48E    W:  89:45:36E   Res: 0:13:12                   
 |   Range of data:    min = 1  max = 6                                       
 |                                                                            
 |   Data Source:                                                             
 |    Vector Map: BMR_bndry_epsg4326 at prcp05216ijk                            
 |    Original scale from vector map: 1:1                                     
 |                                                                            
 |   Data Description:                                                        
 |    generated by v.to.rast                                                  
 |                                                                            
 |   Comments:                                                               
 |    v.to.rast input="BMR_bndry_epsg4326 at prcp05216ijk" layer="1" type="ar\   
 |    ea" output="BMR_bndry_epsg4326_rasterized" use="cat" value=1 memory=\   
 |    300                                                                     
 |         


This is the raster file:

  Type of Map:  raster               Number of Categories: 0               
 |   Data Type:    FCELL                                                      
 |   Rows:         230                                                        
 |   Columns:      230                                                        
 |   Total Cells:  52900                                                      
 |        Projection: Latitude-Longitude                                      
 |            N:  35:29:24N    S:  15:06:36S   Res: 0:13:12                   
 |            E: 140:29:24E    W:  89:53:24E   Res: 0:13:12                   
 |   Range of data:    min = 0  max = 0.002821672                             
 |                   



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