1v.qcount(1) Grass User's Manual v.qcount(1)
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6 v.qcount - indices for quadrat counts of sites lists
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9 vector, statistics
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12 v.qcount
13 v.qcount help
14 v.qcount [-q] input=string [output=string] n=integer r=float
15 [--overwrite]
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17 Flags:
18 -q Quiet
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20 --overwrite
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22 Parameters:
23 input=string
24 vector of points defining sample points
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26 output=string
27 output quadrant centres, number of points is written as category
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29 n=integer
30 number of quadrats
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32 r=float
33 quadrat radius
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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.
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43 This program may not work properly with lat-long data. It uses hypot()
44 in two files: count.c and findquads.c.
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47 v.random
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49 Complete Spatial Randomness and Quadrat Methods - GRASS Tutorial on
50 v.qcount (only available as older file s.qcount-tutorial.ps),
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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.
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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.
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73 Timestamp not working for header part of counts output. (2000-10-28)
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75 Please send all bug fixes and comments to the author or the grass
76 development team.
77 http://grass.itc.it.
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80 James Darrell McCauley ,
81 when he was at: Agricultural Engineering Purdue University
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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)
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86 Last changed: $Date: 2004/12/06 10:45:44 $
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88 Full index
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92GRASS 6.2.2 v.qcount(1)