NAME¶
r.random.cells - Generates random cell values with spatial
dependence.
KEYWORDS¶
raster, random, cell
SYNOPSIS¶
r.random.cells
r.random.cells help
r.random.cells output=
name distance=
float
[
seed=
integer] [--
overwrite] [--
verbose]
[--
quiet]
Flags:¶
- --overwrite
-
Allow output files to overwrite existing files
- --verbose
-
Verbose module output
- --quiet
-
Quiet module output
Parameters:¶
- output=name
-
Name for output raster map
- distance=float
-
Maximum distance of spatial correlation (value(s) >= 0.0)
- seed=integer
-
Random seed (SEED_MIN >= value >= SEED_MAX) (default [random])
DESCRIPTION¶
r.random.cells generates a random sets of cells that are at least
distance apart. The cells are numbered from 1 to the numbers of cells
generated. Random cells will not be generated in areas masked off.
Detailed parameter description¶
- output
-
Random cells. Each random cell has a unique non-zero cell value ranging from
1 to the number of cells generated. The heuristic for this algorithm is to
randomly pick cells until there are no cells outside of the chosen cell's
buffer of radius distance.
- distance
-
Determines the minimum distance the centers of the random cells will be
apart.
- seed
-
Specifies the random seed that r.random.cells will use to generate
the cells. If the random seed is not given, r.random.cells will
get a seed from the process ID number.
NOTES¶
The original purpose for this program was to generate independent random samples
of cells in a study area. The
distance value is the amount of spatial
autocorrelation for the map being studied.
REFERENCES¶
Random Field Software for GRASS by Chuck Ehlschlaeger
As part of my dissertation, I put together several programs that help GRASS (4.1
and beyond) develop uncertainty models of spatial data. I hope you find it
useful and dependable. The following papers might clarify their use:
-
Ehlschlaeger, C.R., Shortridge, A.M., Goodchild, M.F., 1997. Visualizing
spatial data uncertainty using animation. Computers & Geosciences 23,
387-395. doi:10.1016/S0098-3004(97)00005-8
- Modeling Uncertainty in Elevation Data for Geographical Analysis, by
Charles R. Ehlschlaeger, and Ashton M. Shortridge. Proceedings of the 7th
International Symposium on Spatial Data Handling, Delft, Netherlands,
August 1996.
- Dealing with Uncertainty in Categorical Coverage Maps: Defining,
Visualizing, and Managing Data Errors, by Charles Ehlschlaeger and Michael
Goodchild. Proceedings, Workshop on Geographic Information Systems at the
Conference on Information and Knowledge Management, Gaithersburg MD,
1994.
- Uncertainty in Spatial Data: Defining, Visualizing, and Managing Data
Errors, by Charles Ehlschlaeger and Michael Goodchild. Proceedings,
GIS/LIS'94, pp. 246-253, Phoenix AZ, 1994.
SEE ALSO¶
r.random.surface, r.random
AUTHOR¶
Charles Ehlschlaeger; National Center for Geographic Information and Analysis,
University of California, Santa Barbara.
Last changed: $Date: 2011-10-07 21:53:04 +0200 (Fri, 07 Oct 2011) $
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