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**NAME**

v.perturb- Random location perturbations of GRASS vector points

**KEYWORDS**

vector, geometry, statistics

**SYNOPSIS**

v.perturbv.perturbhelpv.perturb[-q]input=nameoutput=name[distribution=string]parameters=float[,float,...] [minimum=float] [seed=integer] [--overwrite] [--verbose] [--quiet]Flags:-qQuiet--overwriteAllow output files to overwrite existing files--verboseVerbose module output--quietQuiet module outputParameters:input=nameVector points to be spatially perturbedoutput=nameName for output vector mapdistribution=stringDistribution of perturbation Options:uniform,normalDefault:uniformparameters=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=floatMinimum deviation in map units Default:0.0seed=integerSeed for random number generation Default:0

**DESCRIPTION**

v.perturbreads a vector map of points and writes the same points butperturbsthe 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 associatedparameteris 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, theminimumparameter 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.randomv.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 usingf2c.Lastchanged:$Date:2011-11-0801:42:51-0800(Tue,08Nov2011)$Full index © 2003-2013 GRASS Development Team