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v.net.allpairs.html
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<h2>DESCRIPTION</h2>
<em>v.net.allpairs</em> computes the shortest path between each selected
node and all other selected nodes. The output is a vector with the
selected nodes and the shortest paths.
<h2>NOTES</h2>
An attribute table is created and linked to layer <em>arc_layer</em>. The
table contains four columns: <em>cat</em>, <em>from_cat</em>,
<em>to_cat</em>, <em>cost</em>.
Each <em>cat</em> entry denotes the category of the shortest path from
the node with category <em>from_cat</em> to the node with category
<em>to_cat</em>. If points are specified by <b>cats, layer</b> or
<b>where</b> parameters then the table is filled only for the selected
points.
<br>
If <b>arc_backward_column</b> is not given then then the same costs are used for
forward and backward arcs.
<h2>EXAMPLE</h2>
Find shortest path along roads from selected archsites (Spearfish sample
dataset):
<div class="code"><pre>
# prepare network: connect archsites to roads with threshold 200
v.net input=roads@PERMANENT points=archsites@PERMANENT \
output=roads_net operation=connect thresh=200
# verify result
v.category input=roads_net option=report
# only lines should have a category in layer 1
# only points should have a category in layer 2
# shortest path between all points with categories 1 - 5 in layer 2
v.net.allpairs input=roads_net cats=1-5 out=roads_net_all
v.db.select roads_net_all
</pre></div>
Result in matrix form:
<div class="code"><pre>
from\to 1 3 4 5
1 0 18820.386 17206.651 17373.274
3 18820.386 0 1739.079 9040.575
4 17206.651 1739.079 0 7426.84
5 17373.274 9040.575 7426.84 0
</pre></div>
<h2>SEE ALSO</h2>
<em>
<a href="v.net.path">v.net.path</a>,
<a href="v.net.distance">v.net.distance</a>
</em>
<h2>AUTHORS</h2>
Daniel Bundala, Google Summer of Code 2009, Student<br>
Wolf Bergenheim, Mentor<br>
Markus Metz