1v.perturb(1)                  Grass User's Manual                 v.perturb(1)
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NAME

6       v.perturb  - Random location perturbations of GRASS vector points
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KEYWORDS

9       vector
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SYNOPSIS

12       v.perturb
13       v.perturb help
14       v.perturb  [-q]  input=name output=name  [distribution=string]  parame‐
15       ters=float[,float,...]   [minimum=float]    [seed=integer]     [--over‐
16       write]  [--verbose]  [--quiet]
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18   Flags:
19       -q
20           Quiet
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22       --overwrite
23           Allow output files to overwrite existing files
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25       --verbose
26           Verbose module output
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28       --quiet
29           Quiet module output
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31   Parameters:
32       input=name
33           Vector points to be spatially perturbed
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35       output=name
36           Name for output vector map
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38       distribution=string
39           Distribution of perturbation
40           Options: uniform,normal
41           Default: uniform
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43       parameters=float[,float,...]
44           Parameter(s)  of distribution. If the distribution is uniform, only
45           one parameter, the maximum, is needed. For a  normal  distribution,
46           two parameters, the mean and standard deviation, are required.
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48       minimum=float
49           Minimum deviation in map units
50           Default: 0.0
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52       seed=integer
53           Seed for random number generation
54           Default: 0
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DESCRIPTION

57       v.perturb  reads  a vector map of points and writes the same points but
58       perturbs the eastings and northings by adding either a uniform or  nor‐
59       mal  delta value. Perturbation means that a variating spatial deviation
60       is added to the coordinates.
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NOTES

63       The uniform distribution is always centered about zero.  The associated
64       parameter  is  constrained  to be positive and specifies the maximum of
65       the distribution; the minimum is the negation  of  that  parameter.  Do
66       perturb  into  a  ring  around the center, the minimum parameter can be
67       used.
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69       Usually, the mean (first parameter) of the normal distribution is  zero
70       (i.e.,  the  distribution  is centered at zero). The standard deviation
71       (second parameter) is naturally constrained to be positive.
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73       Output vector points are not guaranteed to be contained within the cur‐
74       rent geographic region.
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SEE ALSO

77       v.random
78       v.univar
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AUTHOR

81       James Darrell McCauley
82       when he was at: Agricultural Engineering Purdue University
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84       Random  number generators originally written in FORTRAN by Wes Peterson
85       and translated to C using f2c.
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87       Last changed: $Date: 2006-03-03 11:41:45 +0100 (Fri, 03 Mar 2006) $
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89       Full index
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91       © 2003-2008 GRASS Development Team
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95GRASS 6.3.0                                                       v.perturb(1)