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<em>d.correlate</em> is a shell (sh(1)) script that
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graphically displays the results of an
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<em><a href="r.stats.html">r.stats</a></em>
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run on two raster map layers. This shell script is useful
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for highlighting the correlation (or lack of it) among data
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The results are displayed in the active display frame on
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the user's graphics monitor. <em>d.correlate</em> erases
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the active frame before displaying results.
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The <b>layer</b><i>n</i> parameters supply the names of two to
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four existing raster map layers to be included in the correlation.
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This is a shell script that uses <em><a href="r.stats.html">r.stats</a></em>
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and the UNIX <em>awk</em> command to calculate the correlation among data
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layers, and uses <em><a href="d.text.html">d.text</a></em> and
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<em><a href="d.graph.html">d.graph</a></em> to display the results.
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If three or four map layers are specified, the correlation
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among each combination of two data layers is displayed.
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<img src="d_correlate.png" border=1 width="70%"><br>
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Compare LANDSAT-7 bands 2 and 3 in the North Carolina sample dataset,
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and over-plot a trend line:
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<div class="code"><pre>
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g.region rast=lsat7_2002_20
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d.correlate -t layer1=lsat7_2002_20 layer2=lsat7_2002_30 --verbose
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<a href="d.text.html">d.text</a>,
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<a href="d.graph.html">d.graph</a>,
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<a href="r.coin.html">r.coin</a>,
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<a href="r.regression.line.html">r.regression.line</a>,
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<a href="r.stats.html">r.stats</a>
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<a href="http://www.cecer.army.mil/">U.S.Army Construction Engineering
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Research Laboratory</a>
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Rewritten to GRASS 6 (from csh to sh) by Markus Neteler<br>
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Linear regression model and trend line plotting by Hamish Bowman
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<i>Last changed: $Date: 2013-09-22 09:51:30 +0200 (Sun, 22 Sep 2013) $</i>