Geografic-Information-System/display/d.vect.chart/d.vect.chart.html

<h2>DESCRIPTION</h2>

<em>d.vect.chart</em> displays charts for GRASS vector data in the active
frame on the graphics monitor.

<h2>NOTES</h2>

The charts are positioned as follows:
<ul>
<li> vector points: on point position,
<li> vector lines: on line centers,
<li> vector areas: on area centroids.
</ul>

Bar charts are placed with their lower edge starting from the y-coordinate
of the feature being symbolized, and centered with respect to the x-coordinate.
The <b>-c</b> flag can be used to center the bar chart in both x and y
directions.
<p>
The 'sizecol' parameter is proportionate to the radius.
<p>
The optional <b>max_ref</b> parameter accepts a list of values that
represent the maximum value for each column listed in the values for the
parameter <b>columns</b>. These values are used to create a framed bar
plot if <b>chart_type</b> is <em>bar</em> (See Example 2).

<h2>EXAMPLES</h2>

<h3>Example 1</h3>

Pie-charts of monthly winter precipitation (North Carolina sample dataset):

<!-- might be good to add this to example:
v.voronoi input=precip_30ynormals output=precip_stations_voronoi
d.vect precip_stations_voronoi type=boundary
-->

<div class="code"><pre>
g.region vector=nc_state -p
d.vect nc_state
d.vect.chart precip_30ynormals chart_type=pie columns=nov,dec,jan,feb -l

# show pie chart as 3D
d.erase
d.vect nc_state
d.vect.chart precip_30ynormals chart_type=pie columns=nov,dec,jan,feb -l -3
</pre></div>

<center>
<img src="d_vect_chart_pie_2d.png" alt="d.vect.chart 2D pie chart"><br>
2D pie-chart of monthly winter precipitation in North Carolina
</center>
<p>
<center>
<img src="d_vect_chart_pie_3d.png" alt="d.vect.chart 3D pie chart"><br>
3D pie-chart of monthly winter precipitation in North Carolina
</center>

<h3>Example 2</h3>

Bar-chart of different census map values:

<div class="code"><pre>
d.vect.chart map=vectmap columns=cens51,cens61,cens71,cens81 chart_type=bar
</pre></div>

<h3>Example 3</h3>

Creation of framed bar charts of an erodibiliy index from the Spearfish
sample dataset:

<div class="code"><pre>
g.region raster=erode.index -p
r.to.vect -s input=erode.index output=erode_index type=area 
v.extract input=erode_index output=erode_index_ctrds type=centroid 
d.rast aspect
d.vect.chart map=erode_index_ctrds chart_type=bar columns=cat \
             size=10 max_ref=12 scale=0.05 colors=yellow 
d.vect erode_index_ctrds icon=basic/circle fcol=black col=black size=5
</pre></div>

<center>
<img src="d.vect.chart_example.jpg" alt="d.vect.chart example"><br>
Bar charts of an erodibiliy index (spatial subset)
</center>

<h2>SEE ALSO</h2>

<em>
<a href="d.erase.html">d.erase</a>,
<a href="d.vect.html">d.vect</a>,
<a href="d.vect.thematic.html">d.vect.thematic</a>,
<a href="d.what.vect.html">d.what.vect</a>,
<a href="d.rast.html">d.rast</a>
</em>

<h2>AUTHOR</h2>

Radim Blazek, ITC-Irst, Trento, Italy

<p><i>Last changed: $Date$</i>