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 10:42:51 +0100 (Tue, 08 Nov 2011) $ Full index © 2003-2014 GRASS Development Team