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<em>d.thematic.area</em> draws thematic coropleth vector maps based on an attribute column or an expression involving several columns. It takes a number of class breaks (excluding the minimum and maximum values) and a list of colors to apply to the classes (has to be the number of class breaks + 1).
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The <em>-l</em> flag instructs the module to print legend information (class min | class max | number of observations in class | color) to standard output for futher use in graphical software. When given this flag with the <em>-n</em> flag, the module will only print the legend information without drawing the map.
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One can used <em>v.class</em> to supply class breaks for d.thematic.area (see example below);
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<div class="code"><pre>
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d.thematic.area -l map=communes3 data=pop breaks=111393.250000,222785.500000,334177.750000 colors=255:0:0,0:255:0,0:0:255,0,0,0
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The following example uses a calculated attribute (density = pop/area) and v.class to calculate class breaks and feed them directly into d.thematic.area:
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<div class="code"><pre>
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d.thematic.area -l map=communes2 data=pop/area breaks=`v.class -g map=communes2 column=pop/area algo=std nbcla=5` colors=0:0:255,50:100:255,255:100:50,255:0:0,156:0:0
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<EM><A HREF="v.class.html">v.class</A></EM>
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<EM><A HREF="d.vect.html">d.vect</A></EM>
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<EM><A HREF="v.univar.html">v.univar</A></EM>