On Mon, Apr 14, 2014 at 10:50:52AM +0100, Albert Yiamakis wrote:

On 13/04/14 22:02, Alexis Praga wrote:

...

Hi,

I am trying to use metric_tsp_approx on a graph defined as :

typedef adjacency_list<vecS, vecS, undirectedS, City, Road> Graph;

City contains the vertex id and Road the edge weight. After reading the documentation, I arrived to :

metric_tsp_approx(g_init, weight_map(get(&Road::length, g_init)). vertex_index_map(get(&City::id, g_init)), make_tsp_tour_visitor(back_inserter(c)));

I have compilation errors however. The relevant part seems to be :

/usr/include/boost/property_map/property_map.hpp:382:58: error: no type named ‘key_type’ in ‘struct boost::property_traits<boost::bgl_named_params<boost::bundle_property_map<boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, City, Road>, long unsigned int, City, int>, boost::vertex_index_t, boost::no_property> >’

Any help appreciated, thanks.

Are City and Road really properties? get() looks up properties by tag. Supply your adjacency list properties rather than the classes themselves. For instance:

typedef property<vertex_index_t, City> CityProperty; typedef property<edge_index_t, Road> RoadProperty;

typedef adjacency_list<vecS, vecS, undirectedS, CityProperty, RoadProperty> Graph;

Then you can use get(vertex_index_t(), g_init) and get(edge_index_t(), g_init). These are predefined tags - for more and how to define your own:

http://www.boost.org/doc/libs/1_55_0/libs/graph/doc/using_adjacency_list.htm...

Albert

Thanks for the answer. I am a bit confused about properties. From the documentation, I understood you could use any class to create the graph, as long as you use bundled property and as long as you create the property map when needed. I thought it would suffice to create a property map for vertices index and for the edge index. In my case : vertex_index_map(get(&City::id, g_init)), and weight_map(get(&Road::length, g_init)), From your answer, I think you want me to use internal properties, instead of bundled properties. Am I missing something ? -- Alexis Praga, PhD Student (CERFACS) GPG key : AD4A AF6D BB5C 042F 9422 1223 06E1 C1BF E287 65D0

After your first named argument, you need to use named arguments for the rest of the argument list:

metric_tsp_approx(g_init, weight_map(...).vertex_index_map(...).visitor(...));

Fixing that might fix your compilation errors.

-- Jeremiah Willcock

Interestingly, I don't see a named parameter overload in metric_tsp_approx.hpp.

Also, I'm having trouble creating a visitor. I tried :

metric_tsp_approx(g_init, weight_map(get(&Road::length, g_init)).vertex_index_map(get(&City::id, g_init)) .make_tsp_tour_visitor(back_inserter(c)));

But compiling raises the error : has no member named ‘make_tsp_tour_visitor’

Should I create a class for the visitor ?

No, the call should be metric_tsp_approx(g_init, weight_map(get(&Road::length, g_init)).vertex_index_map(get(&City::id, g_init)) .visitor(make_tsp_tour_visitor(back_inserter(c)))); However that doesn't compile either; I suspect because there is no named parameter overload and it tries to call metric_tsp_approx(VertexListGraph& g, TSPVertexVisitor vis) instead. Albert