Re: [Boost-users] Problems to use Boost Graph

Subject: Re: [Boost-users] Problems to use Boost Graph
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2015-07-04 15:30:05

>________________________________
> From: Oodini <svdbg____at_[hidden]>
>To: boost-users_at_[hidden] 
>Sent: Monday, June 29, 2015 10:21 AM
>Subject: [Boost-users] Problems to use Boost Graph
> 
>
>Hello,
>
>I am trying to understand the boost::dijkstra_shortest_paths() function.
>I don't understand the second and third arguments. The documentation says they're supposed to be properties map :
>
>OUT: predecessor_map(PredecessorMap p_map)
>    The predecessor map records the edges in the shortest path tree, the tree
>    computed by the traversal of the graph. Upon completion of the algorithm,
>    the edges (p[u],u) for all u in V are in the tree. The shortest path from
>    vertex s to each vertex v in the graph consists of the vertices v, p[v],
>    p[p[v]], and so on until s is reached, in reverse order. The tree is not
>    guaranteed to be a minimum spanning tree. If p[u] = u then u is either
>    the source vertex or a vertex that is not reachable from the source.
>    The PredecessorMap type must be a Read/Write Property Map whose key and
>    value types are the same as the vertex descriptor type of the graph.
>
>but that doesn't work. I have to use an iterator on the properties map, by using :
>
>boost::make_iterator_property_map(pred_map.begin(),vertex_index)
>
>Does the documentation need reviewers ?

The function requires a property map object, like the one make_iterator_property_map returns.  It does not work directly with a container.  Is there somewhere the documentation says something different from that?

-- Jeremiah Willcock