db.univar.1grass man page

db.univar — Calculates univariate statistics on selected table column.

Keywords

database, statistics, attribute table

Synopsis

db.univar
db.univar --help
db.univar [-eg] table=name column=name [database=name] [driver=name] [where=sql_query] [percentile=float[,float,...]] [--help] [--verbose] [--quiet] [--ui]

Flags

-e
Extended statistics (quartiles and 90th percentile)
-g
Print stats in shell script style
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog

Parameters

table=name [required]
Name of attribute table
column=name [required]
Name of attribute column on which to calculate statistics (must be numeric)
database=name
Name of database
driver=name
Name of database driver
Options: dbf, odbc, ogr, sqlite, pg
where=sql_query
WHERE conditions of SQL statement without ’where’ keyword
Example: income < 1000 and inhab >= 10000
percentile=float[,float,...]
Percentile to calculate (requires extended statistics flag)
Options: 0-100
Default: 90

Description

db.univar calculates basic univariate statistics for numeric attributes in a data table. It will calculate minimum, maximum, range, mean, standard deviation, variance, coefficient of variation, quartiles, median, and 90th percentile. It uses db.select to create list values for statistical calculations. NOTES If the database and driver are not specified, the default values set in db.connect will be used.

Example

In this example, random points are sampled from the elevation map (North Carolina sample dataset) and univariate statistics performed:

g.region raster=elevation -p
v.random output=samples n=100
v.db.addtable samples column="heights double precision"
v.what.rast samples raster=elevation colum=heights
v.db.select samples
db.univar samples colum=heights

See Also

v.db.univar, r.univar, v.univar, db.select, d.vect.thematic

Author

Michael Barton, Arizona State University

and authors of r.univar.sh

Last changed: $Date: 2014-12-19 22:55:37 +0100 (Fri, 19 Dec 2014) $

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