Re: [Boost-users] edges

Subject: Re: [Boost-users] edges
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2010-03-31 10:11:41

On Wed, 31 Mar 2010, Figa Pelosa wrote:

> hello.
> My graph is an:
>
> typedef adjacency_list < mapS, vecS, undirectedS, my_vertexProperty, 
> property < edge_weight_t, float > > Graph;
>
> I have 100 edges, and I also have an array with 100 weights.
>
> How do I assign weight[i] to edge[i], and how do I create a
> weightmap to use in dijkstra_shortest_paths()?

The easiest way would probably be the "obvious" one -- iterate through 
edges(g) and the weight array in parallel, and assign corresponding 
elements.  I.e., (using <boost/graph/iteration_macros.hpp>):

size_t i = 0;
BGL_FORALL_EDGES(e, g, Graph) {
   put(edge_weight, g, e, weight[i]);
   ++i;
}

You could also use your weight array directly by creating an 
iterator_property_map to use as the weight map, but this would require 
filling in an edge_index property map that corresponds to the edge order 
in your weight array.

Since you have an internal edge_weight property in your graph, you can 
leave off the weight_map parameter to dijkstra_shortest_paths; your 
internal property will be found automatically.

-- Jeremiah Willcock