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PODijkstra Shortest Path with VertexList = ListS in boost graph
 

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  1. PODijkstra Shortest Path with VertexList = ListS in boost graph
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    <p>I am quite new to Boost graph. I am trying to adapt an example for finding Dijkstra Shortest Path algorithm which used VertexList = vecS. I changed the vertex container to ListS. I learned that we have to provide our own vertex_index for the algorithm to work if we use listS.</p> <pre><code>int main(int, char *[]) { typedef float Weight; typedef boost::property&lt;boost::edge_weight_t, Weight&gt; WeightProperty; typedef boost::property&lt;boost::vertex_name_t, std::string&gt; NameProperty; typedef boost::property&lt;boost::vertex_index_t, int&gt; IndexProperty; typedef boost::adjacency_list &lt; boost::listS, boost::listS, boost::directedS, NameProperty, WeightProperty &gt; Graph; typedef boost::graph_traits &lt; Graph &gt;::vertex_descriptor Vertex; typedef boost::graph_traits &lt;Graph&gt;::vertex_iterator Viter; typedef boost::property_map &lt; Graph, boost::vertex_index_t &gt;::type IndexMap; typedef boost::property_map &lt; Graph, boost::vertex_name_t &gt;::type NameMap; typedef boost::iterator_property_map &lt; Vertex*, IndexMap, Vertex, Vertex&amp; &gt; PredecessorMap; typedef boost::iterator_property_map &lt; Weight*, IndexMap, Weight, Weight&amp; &gt; DistanceMap; Graph g; Vertex v0 = boost::add_vertex(std::string("v0"), g); Vertex v1 = boost::add_vertex(std::string("v1"), g); Vertex v2 = boost::add_vertex(std::string("v2"), g); Vertex v3 = boost::add_vertex(std::string("v3"), g); Weight weight0 = 5; Weight weight1 = 3; Weight weight2 = 2; Weight weight3 = 4; boost::add_edge(v0, v1, weight0, g); boost::add_edge(v1, v3, weight1, g); boost::add_edge(v0, v2, weight2, g); boost::add_edge(v2, v3, weight3, g); std::vector&lt;Vertex&gt; predecessors(boost::num_vertices(g)); // To store parents std::vector&lt;Weight&gt; distances(boost::num_vertices(g)); // To store distances IndexMap indexMap; // = boost::get(boost::vertex_index, g); NameMap name; Viter i, iend; //Create our own vertex index. This is what I changed in the original code int c = 0; for (boost::tie(i, iend) = vertices(g); i != iend; ++i, ++c) { indexMap[*i] = c; // **Error points to this line** name[*i] = 'A' + c; } PredecessorMap predecessorMap(&amp;predecessors[0], indexMap); DistanceMap distanceMap(&amp;distances[0], indexMap); boost::dijkstra_shortest_paths(g, v0, boost::distance_map(distanceMap).predecessor_map(predecessorMap)); // Extract a shortest path std::cout &lt;&lt; std::endl; typedef std::vector&lt;Graph::edge_descriptor&gt; PathType; PathType path; Vertex v = v3; for(Vertex u = predecessorMap[v]; u != v; // Keep tracking the path until we get to the source v = u, u = predecessorMap[v]) // Set the current vertex to the current predecessor, and the predecessor to one level up { std::pair&lt;Graph::edge_descriptor, bool&gt; edgePair = boost::edge(u, v, g); Graph::edge_descriptor edge = edgePair.first; path.push_back( edge ); } // Write shortest path std::cout &lt;&lt; "Shortest path from v0 to v3:" &lt;&lt; std::endl; float totalDistance = 0; for(PathType::reverse_iterator pathIterator = path.rbegin(); pathIterator != path.rend(); ++pathIterator) { std::cout &lt;&lt; name[boost::source(*pathIterator, g)] &lt;&lt; " -&gt; " &lt;&lt; name[boost::target(*pathIterator, g)] &lt;&lt; " = " &lt;&lt; boost::get( boost::edge_weight, g, *pathIterator ) &lt;&lt; std::endl; } std::cout &lt;&lt; std::endl; std::cout &lt;&lt; "Distance: " &lt;&lt; distanceMap[v3] &lt;&lt; std::endl; return EXIT_SUCCESS; } </code></pre> <p>I get the following error:</p> <p>/spvec.cpp:62:20: error: no match for ‘operator=’ in ‘index.boost::adj_list_vertex_property_map::operator[] [with Graph = boost::adjacency_list >, boost::property >, ValueType = boost::detail::error_property_not_found, Reference = boost::detail::error_property_not_found&amp;, Tag = boost::vertex_index_t, boost::adj_list_vertex_property_map::key_type = void*](i.std::_List_iterator&lt;_Tp>::operator* with _Tp = void*, _Tp&amp; = void*&amp;) = c’</p> <p>I am sure I made a mistake in creating my own vertex index. But couldn´t find out exactly what´s the issue. Does anyone have some suggestions on what I am doing wrong.. </p>
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    1. COCan you post the error?
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    2. COWithout knowing the error, it's a needle in the haystack, and the needle might not even be in that code snippet.
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      1. USAnne Quinn
 

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