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) $

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       © 2003-2013 GRASS Development Team