NAME

       v.random  - Randomly generate a 2D/3D vector points map.

KEYWORDS

       vector, statistics

SYNOPSIS

       v.random
       v.random help
       v.random  [-zdb]  output=name  n=integer   [zmin=float]    [zmax=float]   [column=string]   [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       -z
           Create 3D output

       -d
           Use drand48() function instead of rand()

       -b
           Do not build topology

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       output=name
           Name for output vector map

       n=integer
           Number of points to be created

       zmin=float
           Minimum z height (needs -z flag or column name)
           Default: 0.0

       zmax=float
           Maximum z height (needs -z flag or column name)
           Default: 0.0

       column=string
           Column name and type (i.e. INTEGER, DOUBLE PRECISION) for z values
           If type is not given then DOUBLE PRECISION is used. Writes Z data to column instead of 3D vector.

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.

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'
        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 ,
       when he was at: Agricultural Engineering Purdue University

       Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $

       Full index

       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                                     v.random(1grass)