- Calculates univariate statistics from a raster map based on a vector map and uploads statistics to new attribute columns.
, univariate statistics
, zonal statistics
v.rast.stats [-cd] map=name [layer=string] [where=sql_query] raster=name[,name,...] column_prefix=string[,string,...] [method=string[,string,...]] [percentile=integer] [--help] [--verbose] [--quiet] [--ui]
- Continue if upload column(s) already exist
- Create densified lines (default: thin lines)
- All cells touched by the line will be set, not only those on the render path
- Print usage summary
- Verbose module output
- Quiet module output
- Force launching GUI dialog
- map=name [required]
- Name of vector map
- Or data source for direct OGR access
- Layer number or name
- Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
- Default: 1
- WHERE conditions of SQL statement without 'where' keyword
- Example: income < 1000 and population >= 10000
- raster=name[,name,...] [required]
- Name of input raster map to calculate statistics from
- column_prefix=string[,string,...] [required]
- Column prefix for new attribute columns
- The methods to use
- Options: number, null_cells, minimum, maximum, range, average, stddev, variance, coeff_var, sum, first_quartile, median, third_quartile, percentile
- Default: number,null_cells,minimum,maximum,range,average,stddev,variance,coeff_var,sum,first_quartile,median,third_quartile,percentile
- Percentile to calculate
- Options: 0-100
- Default: 90
calculates basic univariate statistics from
a raster map only for the parts covered by the specified vector map.
The vector map will be rasterized according to the raster map resolution.
Then univariate statistics are calculated per vector category (cat) from
the raster map and the results uploaded to the vector map attribute table.
A new column is generated in the attribute table for each statistic requested
(if not already present).
The univariate statistics include the number of raster cells counted,
the number of raster NULL cells counted, minimum
and maximum cell values, range, average,
standard deviation, variance, coefficient of variation, sum, first quartile,
median, third quartile, and percentile.
is only meaningful for lines or polygons.
The module may take a long time to run if the raster region contains a large
number of cells. In this case the --verbose flag may be used to track
The script stops if a (prefixed) upload column is already present in the
vector map attribute table, unless otherwise instructed with the -c
continue flag. The column prefix will be separated from the statistic name
with an underscore. For example with a prefix of "elev" the sum
column will be named elev_sum.
If a DBF database is being used, note that column names are restricted by the
DBF specification to 10 characters. Therefore it is advised to be economical
in the use of the column prefix when using DBF as any additional characters
will be chopped off.
If a MASK is present, it will be restored after the script finished.
The script changes temporarily to the resolution of the given raster map.
Large amounts of system memory can be used when extended statistics
(first_quartile,median,third_quartile,percentile ) are being requested
with a very large region setting. If the region is too large the module
should display memory allocation errors. Basic statistics can be calculated
using any size input region.
Example to upload DEM statistics to ZIP codes vector map
(North Carolina sample dataset):
# set computational region to DEM:
g.region raster=elevation -p
# calculate selected DEM statistics, upload to vector map table:
v.rast.stats myzipcodes_wake raster=elevation \
column_prefix=elev method=minimum,maximum,average,range,stddev,percentile \
# verify results:
v.info -c myzipcodes_wake
v.univar myzipcodes_wake column=elev_range type=centroid
Markus Neteler, CEA (for the EDEN EU/FP6 Project
Last changed: $Date$
Available at: v.rast.stats source code (history)
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