Re: [Boost-Users] BGL: Own vertex index property

From: Jeremy Siek (jsiek_at_[hidden])
Date: 2002-07-12 13:17:18

Hi Michael,

On Fri, 12 Jul 2002, Michael Kettner wrote:
kettne> Hi Jeremy,
kettne>
kettne> thanks for your quick reply.
kettne> What I do is the following: I wrote my own class representing nodes (class
kettne> myNodeClass). Now I'm creating nodes in a graph, mapping each resulting
kettne> vertex index to the associated myNode-object in a std::map. I hope the
kettne> following code fragment is enough to give you an idea:
kettne>

That's a tough one. The easiest solution I see is switching to
VertexList=listS. Do you have a reason for prefering vecS?

This issue has me thinking... I see a way to change
adjacency_list<VertexList=vecS> so that the vertex descriptors are stable.
Now the trick is to think of a way to make this backwards compatible...
Don't hold your breadth on this though... this would be a fairly large
change to adjacency_list.

kettne> And another question: I tried to run boost::dijkstra_shortest_paths on myGraph
kettne> with "listS" as VertexList template parameter, but the code fails to compile.
kettne> When using "vecS" instead, everything works fine. Any idea?

Yeah, dijkstra_shortest_paths requires a vertex_index property map, which
is by default obtained from the graph. You need to add vertex_index_t as a
internal vertex property for your graph and initialize it with appropriate
integers.

Cheers,
Jeremy

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 Jeremy Siek                          http://php.indiana.edu/~jsiek/
 Ph.D. Student, Indiana Univ. B'ton   email: jsiek_at_[hidden]
 C++ Booster (http://www.boost.org)   office phone: [phone]
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