NAME

       v.qcount  - Indices for quadrat counts of sites lists.

KEYWORDS

       vector, statistics

SYNOPSIS

       v.qcount
       v.qcount help
       v.qcount   [-gq]   input=string    [output=string]    n=integer   r=float    [--overwrite]
       [--verbose]  [--quiet]

   Flags:
       -g
           Print results in shell script style

       -q
           Quiet

       --overwrite
           Allow output files to overwrite existing files

       --verbose
           Verbose module output

       --quiet
           Quiet module output

   Parameters:
       input=string
           Vector of points defining sample points

       output=string
           Output quadrant centres, number of points is written as category

       n=integer
           Number of quadrats

       r=float
           Quadrat radius

DESCRIPTION

       v.qcount chooses n circular quadrats of radius r such that they are completely within  the
       bounds  of  the  current region and no two quadrats overlap.  The number of points falling
       within each quadrat are counted and indices are calculated to estimate  the  departure  of
       point locations from complete spatial randomness.

NOTES

       This  program  may  not  work  properly  with lat-long data. It uses hypot() in two files:
       count.c and findquads.c.

SEE ALSO

       v.random

       Complete Spatial Randomness and Quadrat  Methods   -  GRASS  Tutorial  on  v.qcount  (only
       available as older file s.qcount-tutorial.ps),

       General references include:
       Noel  A.  C.  Cressie.   Statistics  for  Spatial  Data.   Wiley Series in Probability and
       Mathematical Statistics. John Wiley & Sons, New York, NY, 1st edition, 1991.
       Brian D. Ripley.  Spatial Statistics. John Wiley \& Sons, New York, NY, 1981.

       References to the indices include:
       F. N. David and P. G. Moore.  Notes on  contagious  distributions  in  plant  populations.
       Annals of Botany, 18:47-53, 1954.
       J. B. Douglas.  Clustering and aggregation.  Sankhya B, 37:398-417, 1975.
       R.  A. Fisher, H. G. Thornton, and W. A. Mackenzie.  The accuracy of the plating method of
       estimating the density of bacterial populations.  Annals of  Applied  Biology,  9:325-359,
       1922.
       M. Lloyd. Mean crowding.  Journal of Animal Ecology, 36:1-30, 1967.
       M.  Morista.  Measuring the dispersion and analysis of distribution patterns.  Memoires of
       the Faculty of Science, Kyushu University, Series E.  Biology, 2:215-235, 1959.

BUGS

       Timestamp not working for header part of counts output. (2000-10-28)

       Please send all bug fixes and comments to the author or the grass development team.
       http://grass.osgeo.org.

AUTHORS

       James Darrell McCauley ,
       when he was at: Agricultural Engineering Purdue University

       Modified for GRASS 5.0 by Eric G. Miller (2000-10-28)
       Modified for GRASS 5.7 by R. Blazek (2004-10-14)

       Last changed: $Date: 2011-11-08 01:42:51 -0800 (Tue, 08 Nov 2011) $

       Full index

       © 2003-2013 GRASS Development Team