NAME¶
v.perturb - Random location perturbations of GRASS vector points
KEYWORDS¶
vector, geometry, statistics
SYNOPSIS¶
v.perturb
v.perturb help
v.perturb [-
q]
input=
name output=
name
[
distribution=
string]
parameters=
float[,
float,...] [
minimum=
float] [
seed=
integer]
[--
overwrite] [--
verbose] [--
quiet]
Flags:¶
- -q
-
Quiet
- --overwrite
-
Allow output files to overwrite existing files
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- input=name
-
Vector points to be spatially perturbed
- output=name
-
Name for output vector map
- distribution=string
-
Distribution of perturbation
Options: uniform,normal
Default: uniform
- parameters=float[,float,...]
-
Parameter(s) of distribution. If the distribution is uniform, only one
parameter, the maximum, is needed. For a normal distribution, two
parameters, the mean and standard deviation, are required.
- minimum=float
-
Minimum deviation in map units
Default: 0.0
- seed=integer
-
Seed for random number generation
Default: 0
DESCRIPTION¶
v.perturb reads a vector map of points and writes the same points but
perturbs the eastings and northings by adding either a uniform or
normal delta value. Perturbation means that a variating spatial deviation is
added to the coordinates.
NOTES¶
The uniform distribution is always centered about zero. The associated
parameter is constrained to be positive and specifies the maximum of
the distribution; the minimum is the negation of that parameter. Do perturb
into a ring around the center, the
minimum parameter can be used.
Usually, the mean (first parameter) of the normal distribution is zero (i.e.,
the distribution is centered at zero). The standard deviation (second
parameter) is naturally constrained to be positive.
Output vector points are not guaranteed to be contained within the current
geographic region.
SEE ALSO¶
v.random
v.univar
AUTHOR¶
James Darrell McCauley
when he was at: Agricultural Engineering Purdue University
Random number generators originally written in FORTRAN by Wes Peterson and
translated to C using
f2c.
Last changed: $Date: 2011-11-08 10:42:51 +0100 (Tue, 08 Nov 2011) $
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