NAME
v.perturb - Random location perturbations of GRASS sites.
SYNOPSIS
v.perturb
v.perturb help
v.perturb [-q] input=string output=string [distribution=string] parameters=float[,float,...]
Flags:
- -q
- Quiet
Parameters:
- input=string
- vector points to be perturbed
- output=string
- vector to save output
- 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.
DESCRIPTION
s.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.
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 sites are not guaranteed to be contained within the
current geographic region.
SEE ALSO
v.random
v.univar
AUTHOR
James Darrell McCauley
<darrell@mccauley-usa.com>,
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: 2004/10/16 10:26:48 $
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