v.perturb - Random location perturbations of vector points.

       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.

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.

Random,uniformlydistributedselection
       To create a random, uniformly distributed selection of possible new points with a radius of  100,000  map
       units, use the following command:
       v.perturb input=comm_colleges output=uniform_perturb parameters=100000
       Your map should look similar to this figure:
       Figure:Mapshowingtheactualcommunitycollegepointsanduniformlyrandomchosenpoints.Normaldistributedselection
       For a normal distribution with a mean of 5000 and standard deviation of 2000, use the following command:
       v.perturb input=comm_colleges output=normal_perturb distribution=normal parameters=5000,2000
       Figure:Mapshowingtheactualcommunitycollegepointsandnormallyrandomchosenandcoloredpoints.Noticethateachpointisclosertotheoriginalpoint.Normaldistributedselectionwithaminimumvalue
       In order to include a minimum value of 500, use the following command:
       v.perturb input=comm_colleges output=min_perturb distribution=normal parameters=100000,1000 minimum=500

       vector, geometry, statistics, random, point pattern, level1

v.perturb  - Random location perturbations of vector points.

       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.

v.random,v.univar

       Available at: v.perturb source code (history)

       Accessed: Friday Apr 04 01:20:32 2025

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       © 2003-2025 GRASS Development Team, GRASS GIS 8.4.1 Reference Manual

GRASS 8.4.1                                                                                    v.perturb(1grass)

v.perturbv.perturb--helpv.perturb       [-sb]       input=name       [layer=string]       output=name       [distribution=string]
       parameters=float[,float,...]  [minimum=float]    [seed=integer]    [--overwrite]   [--help]   [--verbose]
       [--quiet]  [--ui]

   Flags:-s
           Generate random seed (result is non-deterministic)

       -b
           Do not build topology
           Advantageous when handling a large number of points

       --overwrite
           Allow output files to overwrite existing files

       --help
           Print usage summary

       --verbose
           Verbose module output

       --quiet
           Quiet module output

       --ui
           Force launching GUI dialog

   Parameters:input=name[required]
           Name of input vector map
           Or data source for direct OGR access

       layer=string
           Layer number or name (’-1’ for all layers)
           A  single vector map can be connected to multiple database tables. This number determines which table
           to use. When used with direct OGR access this is the layer name.
           Default: -1output=name[required]
           Name for output vector map

       distribution=string
           Distribution of perturbation
           Options: uniform,normal
           Default: uniformparameters=float[,float,...] [required]
           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: 0.0seed=integer
           Seed for random number generation