[GRASS-SVN] r70118 - grass/trunk/vector/v.qcount
svn_grass at osgeo.org
svn_grass at osgeo.org
Thu Dec 22 06:40:49 PST 2016
Author: neteler
Date: 2016-12-22 06:40:49 -0800 (Thu, 22 Dec 2016)
New Revision: 70118
Added:
grass/trunk/vector/v.qcount/v_qcount_1.png
grass/trunk/vector/v.qcount/v_qcount_2.png
grass/trunk/vector/v.qcount/v_qcount_3.png
grass/trunk/vector/v.qcount/v_qcount_4.png
grass/trunk/vector/v.qcount/v_qcount_5.png
Modified:
grass/trunk/vector/v.qcount/
grass/trunk/vector/v.qcount/v.qcount.html
Log:
v.qcount manual: integration of material https://trac.osgeo.org/grass/browser/grass/branches/releasebranch_5_4/src/sites/s.qcount/tutorial (contributed by pvanbosgeo)
Property changes on: grass/trunk/vector/v.qcount
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Modified: grass/trunk/vector/v.qcount/v.qcount.html
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--- grass/trunk/vector/v.qcount/v.qcount.html 2016-12-21 19:25:05 UTC (rev 70117)
+++ grass/trunk/vector/v.qcount/v.qcount.html 2016-12-22 14:40:49 UTC (rev 70118)
@@ -1,15 +1,57 @@
<h2>DESCRIPTION</h2>
-<em>v.qcount</em> chooses <b>nquadradius ants</b> circular quadrats of
-radius <b>radius</b> 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.
+<em>v.qcount</em> computes six different quadrat count statistics that provide
+a measure of how much an user defined point pattern departs from a complete
+spatial random point pattern.
+<p>Points are distributed following a complete spatial randomness (CSR) pattern
+if events are equally likely to occur anywhere within an area. There are two
+types departure from a CSR: regularity and clustering. Figure 1 gives an example
+of a complete random, regular and a clustered pattern.
+
+<!-- source of figures:
+ https://trac.osgeo.org/grass/browser/grass/branches/releasebranch_5_4/src/sites/s.qcount/tutorial
+-->
+
+<div align="center" style="margin: 10px">
+<img src="v_qcount_1.png">
+<img src="v_qcount_2.png">
+<img src="v_qcount_3.png">
+<br>
+<i>Figure 1: Realization of two-dimensional Poisson processes of 50 points on
+the unit square exhibiting (a) complete spatial randomness, (b) regularity, and
+(c) clustering.</i>
+</div>
+
+<p>Various indices and statistics measure departure from CSR. The
+<em>v.qcount</em> function implements six different <i>quadrat count</i>
+indices that are described in Cressie (1991; p. 590-591)[1] and in Ripley (1981;
+p. 102-106)[2] and summarized in Table 1.
+
+<div align="center" style="margin: 10px">
+<img src="v_qcount_5.png">
+<br>
+<i>Table 1: Indices for Quadrat Count Data. Adapted from
+Cressie [1], this table shows the statistics computed for the
+quadrats in Figure 2.</i>
+</div>
+
+<p>These indices are computed as follows: <em>v.qcount</em> chooses
+<b>nquadrads</b> circular quadrats of radius <b>radius</b> 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. This is illustrated in Figure 2.
+
+<div align="center" style="margin: 10px">
+<img src="v_qcount_4.png">
+<br>
+<i>Figure 2: Randomly placed quadrats (n = 100) with 584 sample points.</i>
+</div>
+
<h2>NOTES</h2>
-This program may not work properly with lat-long data. It uses
+This program may not work properly with lat-long data. It uses
<em>hypot()</em> in two files: <em>count.c</em> and
<em>findquads.c</em>.
@@ -17,50 +59,52 @@
<h2>SEE ALSO</h2>
-<em><a href="v.random.html">v.random</a></em>
+<em><a href="v.random.html">v.random</a></em>
<h2>REFERENCES</h2>
-<ul>
-<li><em>Complete Spatial Randomness and Quadrat Methods</em> - GRASS
-Tutorial on <em>v.qcount</em> (only available as older file
-s.qcount-tutorial.ps)</li>
-</ul>
+<b>General references include:</b>
+<p>[1] Noel A. C. Cressie. <em>Statistics for Spatial Data</em>.
+Wiley Series in Probability and Mathematical Statistics. John Wiley
+& Sons, New York, NY, 1st edition, 1991.
+<p>[2] Brian D. Ripley. <em>Spatial Statistics</em>.
+John Wiley \& Sons, New York, NY, 1981.
+
+
<p>
-General references include:
+<b>References to the indices include:</b>
-<ul>
-<li>Noel A. C. Cressie. <em>Statistics for Spatial Data</em>.
-Wiley Series in Probability and Mathematical Statistics. John Wiley
-& Sons, New York, NY, 1st edition, 1991.</li>
-<li>Brian D. Ripley. <em>Spatial Statistics</em>.
-John Wiley \& Sons, New York, NY, 1981.</li>
-</ul>
+<p>[3] R. A. Fisher, H. G. Thornton, and W. A. Mackenzie.
+The accuracy of the plating method of estimating the density of
+bacterial populations.
+<em>Annals of Applied Biology</em>, 9:325-359, 1922.
+<p>[4] F. N. David and P. G. Moore. Notes on contagious distributions in
+plant populations. <em>Annals of Botany</em>, 18:47-53, 1954.
+
+<p>[5] J. B. Douglas. Clustering and aggregation.
+<em>Sankhya B</em>, 37:398-417, 1975.
+
+<p>[6] M. Lloyd. Mean crowding.
+<em>Journal of Animal Ecology</em>, 36:1-30, 1967.
+
+<p>[7] M. Morista. Measuring the dispersion and analysis of distribution
+patterns. <em>Memoires of the Faculty of Science, Kyushu University, Series E.
+Biology</em>, 2:215-235, 1959.
+
<p>
-References to the indices include:
+<b>A more detailed background is given in the tutorial:</b>
-<ul>
-<li>F. N. David and P. G. Moore. Notes on contagious distributions in
-plant populations. <em>Annals of Botany</em>, 18:47-53, 1954.</li>
+<!-- source of tutorial:
+ https://trac.osgeo.org/grass/browser/grass/branches/releasebranch_5_4/src/sites/s.qcount/tutorial
+-->
-<li>J. B. Douglas. Clustering and aggregation.
-<em>Sankhya B</em>, 37:398-417, 1975.</li>
+<p>[8] James Darrell McCauley 1993. Complete Spatial Randomness and Quadrat Methods -
+<a href="https://grass.osgeo.org/uploads/grass/history_docs/v_qcount_tutorial.pdf">GRASS Tutorial on v.qcount</a>
-<li>R. A. Fisher, H. G. Thornton, and W. A. Mackenzie.
-The accuracy of the plating method of estimating the density of
-bacterial populations.
-<em>Annals of Applied Biology</em>, 9:325-359, 1922.</li>
-<li>M. Lloyd. Mean crowding.
-<em>Journal of Animal Ecology</em>, 36:1-30, 1967.</li>
-<li>M. Morista. Measuring the dispersion and analysis of distribution patterns.
-<em>Memoires of the Faculty of Science, Kyushu University, Series E.
-Biology</em>, 2:215-235, 1959.</li>
-</ul>
-
<h2>KNOWN ISSUES</h2>
Timestamp not working for header part of counts output. (2000-10-28)
@@ -68,8 +112,7 @@
<h2>AUTHORS</h2>
<a href="http://mccauley-usa.com/">James Darrell McCauley</a>
-<a href="mailto:darrell at mccauley-usa.com"><darrell at mccauley-usa.com></a>,
-<br>when he was at:
+<br>when he was at:
<a href="http://ABE.www.ecn.purdue.edu/ABE/">Agricultural Engineering</a>
<a href="http://www.purdue.edu/">Purdue University</a>
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