1v.qcount(1)                   Grass User's Manual                  v.qcount(1)
2
3
4

NAME

6       v.qcount  - indices for quadrat counts of sites lists
7

KEYWORDS

9       vector, statistics
10

SYNOPSIS

12       v.qcount
13       v.qcount help
14       v.qcount   [-q]   input=string    [output=string]    n=integer  r=float
15       [--overwrite]
16
17   Flags:
18       -q  Quiet
19
20       --overwrite
21
22   Parameters:
23       input=string
24           vector of points defining sample points
25
26       output=string
27           output quadrant centres, number of points is written as category
28
29       n=integer
30           number of quadrats
31
32       r=float
33           quadrat radius
34

DESCRIPTION

36       v.qcount chooses n circular quadrats of radius r  such  that  they  are
37       completely  within the bounds of the current region and no two quadrats
38       overlap.  The number of points falling within each quadrat are  counted
39       and indices are calculated to estimate the departure of point locations
40       from complete spatial randomness.
41

NOTES

43       This program may not work properly with lat-long data. It uses  hypot()
44       in two files: count.c and findquads.c.
45

SEE ALSO

47       v.random
48
49       Complete  Spatial  Randomness  and Quadrat Methods  - GRASS Tutorial on
50       v.qcount (only available as older file s.qcount-tutorial.ps),
51
52       General references include:
53       Noel A. C. Cressie.  Statistics for  Spatial  Data.   Wiley  Series  in
54       Probability  and  Mathematical Statistics. John Wiley & Sons, New York,
55       NY, 1st edition, 1991.
56       Brian D. Ripley.  Spatial Statistics.  John Wiley \&  Sons,  New  York,
57       NY, 1981.
58
59       References to the indices include:
60       F.  N.  David  and  P.  G. Moore.  Notes on contagious distributions in
61       plant populations.  Annals of Botany, 18:47-53, 1954.
62       J. B. Douglas.  Clustering and  aggregation.   Sankhya  B,  37:398-417,
63       1975.
64       R. A. Fisher, H. G. Thornton, and W. A. Mackenzie.  The accuracy of the
65       plating method of estimating  the  density  of  bacterial  populations.
66       Annals of Applied Biology, 9:325-359, 1922.
67       M. Lloyd.  Mean crowding.  Journal of Animal Ecology, 36:1-30, 1967.
68       M. Morista.  Measuring the dispersion and analysis of distribution pat‐
69       terns.  Memoires of the Faculty of Science, Kyushu  University,  Series
70       E.  Biology, 2:215-235, 1959.
71

BUGS

73       Timestamp not working for header part of counts output. (2000-10-28)
74
75       Please  send  all  bug  fixes  and  comments to the author or the grass
76       development team.
77       http://grass.itc.it.
78

AUTHOR

80       James Darrell McCauley ,
81       when he was at: Agricultural Engineering Purdue University
82
83       Modified for GRASS 5.0 by Eric G. Miller (2000-10-28)
84       Modified for GRASS 5.7 by R. Blazek (2004-10-14)
85
86       Last changed: $Date: 2004/12/06 10:45:44 $
87
88       Full index
89
90
91
92GRASS 6.2.2                                                        v.qcount(1)
Impressum