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) $

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       © 2003-2013 GRASS Development Team