v.perturb.1grass - Man Page

-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

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: -1

output=name [required]

Name for output vector map

distribution=string

Distribution of perturbation
Options: uniform, normal
Default: uniform

parameters=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: 0.0

seed=integer

Seed for random number generation

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: Map showing the actual community college points and uniformly random chosen points.

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: Map showing the actual community college points and normally random chosen and colored points. Notice that each point is closer to the original point.

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