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#### 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.

```

#### SEEALSO

```       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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