DESCRIPTION

v.random randomly generates vector points within the current region using the selected random number generator.

v.random can generate also 3D vector points or write random value to attribute table. Point height range or attribute value range is controlled by specifying zmin and zmax values. Both z values are included in range (zmin >= z <= zmax). Generated random attribute value type can be controlled by column data type. Use INTEGER column type for integers and DOUBLE PRECISION for floating point numbers. Integer values are calculated by rounding random floating point number.

To produce repeatable results a random seed can be set using the option seed>.

EXAMPLES

Generate 20 random points with binary attribute (only 0 or 1): 
v.random output=binary_random n=20 zmin=0 zmax=1 column='binary INTEGER'
Generate 20 random 3d points with height attribute [0:20] and specific random seed: 
v.random seed=501 output=height_random n=20 zmin=0 zmax=1 column=height
Get 20 random samples from raster map: 
v.random output=random_samples n=20
v.db.addtable map=random_samples layer=1 columns='cat INTEGER, sample DOUBLE PRECISION'
v.what.rast vector=random_samples raster=elevation.10m@PERMANENT layer=1 column=sample
Generate 20 random points and sample attribute data from geology (vector) map: 
v.random output=random_samples n=20
v.db.addtable map=random_samples layer=1 columns='cat integer, geology varchar(100)'
v.what.vect vector=random_samples layer=1 column=geology qvector=geology@PERMANENT qlayer=1 qcolumn=label

SEE ALSO

UNIX man pages for rand(3) and drand48(3).

g.region, r.random, v.perturb, v.sample v.what.rast v.what.vect

BUGS

The RNG used by v.perturb should probably be added to this program.

AUTHOR

James Darrell McCauley <darrell@mccauley-usa.com>,
when he was at: Agricultural Engineering Purdue University

Last changed: $Date$