README

/****************************************************************************
 *
 * MODULE:       r.random.cells
 * AUTHOR(S):    Charles Ehlschlaeger; National Center for Geographic 
 *               Information and Analysis, University of California, Santa
 *               Barbara (original contributor)
 *               Markus Neteler <neteler itc.it>
 *               Roberto Flor <flor itc.it>,
 *               Brad Douglas <rez touchofmadness.com>, 
 *               Glynn Clements <glynn gclements.plus.com>Markus Neteler <neteler itc.it> (original contributor)
 *               Bernhard Reiter <bernhard intevation.de>
 * PURPOSE:      generates a random sets of cells that are at least
 *               some distance apart
 * COPYRIGHT:    (C) 2000-2004 by the GRASS Development Team
 *
 *               This program is free software under the GNU General Public
 *               License (>=v2). Read the file COPYING that comes with GRASS
 *               for details.
 *
 *****************************************************************************/

r.random.cells generates a random sets of cells that are at least
some distance apart. The cells are numbered from 1 to the numbers of
cells generated.  Random cells will not be generated in areas masked off.

OPTIONS
-q
This flag prevents the program from sending a verbose description to standard
output of what the program is doing.

-output

Output map: 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 \fIdistance\fR.

-distance
Input value(s) [default 0.0]: distance determines the minimum distance
the centers of the random cells will be apart. 

-seed
Input value [default: random]: Specifies the random seed that
r.random.cells will use to generate the cells.  If the random seed
is not given, then it 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 distancevalue is the amount
of spatial autocorrelation for the map being studied.