NAME

       v.qcount  - Indices for quadrat counts of vector point lists.

KEYWORDS

       vector, statistics, point pattern

SYNOPSIS

       v.qcount
       v.qcount --help
       v.qcount  [-g]  input=name  [layer=string]   [output=name]  nquadrats=integer radius=float  [--overwrite]
       [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       -g
           Print results in shell script style

       --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

   Parameters:
       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
           Name for output quadrat centers map (number of points is written as category)

       nquadrats=integer [required]
           Number of quadrats

       radius=float [required]
           Quadrat radius

DESCRIPTION

       v.qcount chooses nquadradius ants circular quadrats of radius radius 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

REFERENCES

           •   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.

KNOWN ISSUES

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

AUTHORS

       James Darrell McCauley <darrell@mccauley-usa.com>,
       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: 2015-05-11 02:16:13 +0200 (Mon, 11 May 2015) $

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       © 2003-2016 GRASS Development Team, GRASS GIS 7.0.3 Reference Manual

GRASS 7.0.3                                                                                     v.qcount(1grass)