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 01:42:51 -0800 (Tue, 08 Nov 2011) $

       Full index

       © 2003-2013 GRASS Development Team

GRASS 6.4.3                                                                                    v.perturb(1grass)