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: 20111108 01:42:51 0800 (Tue, 08 Nov 2011) $
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© 20032013 GRASS Development Team
