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 12:29:50 +0100 (Tue, 08 Nov 2011) $
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© 2003-2011 GRASS Development Team