Logan Byers Logan Byers - 1 month ago 11
C++ Question

Copy adjacency_list to different VertexList and EdgeList template

I am having trouble converting or copying a

boost::adjacency_list<setS, setS, undirectedS, int, float>
to a
boost::adjacency_list<vecS, vecS, undirectedS, int, float>
so I can use it for
boost::connected_components
. I cannot control the
VertexList
and
EdgeList
template arguments being
boost::setS
from the outside API so I am trying to work around that.

Minimal example



#include <vector>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/connected_components.hpp>
#include <boost/graph/copy.hpp>

typedef boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, uint32_t, float> AdjacencyList;
typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, uint32_t, float> AdjacencyListWithVec;


typedef AdjacencyList::vertex_descriptor VertexID;


int main(int argc, char** argv)
{
AdjacencyList adj;
VertexID id_0 = boost::add_vertex(adj);
VertexID id_1 = boost::add_vertex(adj);
VertexID id_2 = boost::add_vertex(adj);
VertexID id_3 = boost::add_vertex(adj);
boost::add_edge(id_0, id_1, 1.0f, adj);
boost::add_edge(id_2, id_3, 2.0f, adj);

AdjacencyListWithVec adj_vec;

boost::copy_graph(adj, adj_vec); // won't compile

std::vector<uint32_t> component(4);
size_t num_components = boost::connected_components (adj_vec, &component[0]);

}


g++ error truncated



/usr/include/boost/graph/detail/adjacency_list.hpp: In instantiation of 'struct boost::adj_list_any_vertex_pa::bind_<boost::vertex_index_t, boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>, int>':
/usr/include/boost/graph/detail/adjacency_list.hpp:2613:12: required from 'struct boost::detail::adj_list_choose_vertex_pa<boost::vertex_index_t, boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>, int>'
/usr/include/boost/graph/detail/adjacency_list.hpp:2750:12: required from 'struct boost::adj_list_vertex_property_selector::bind_<boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>, int, boost::vertex_index_t>'
/usr/include/boost/graph/properties.hpp:201:12: required from 'struct boost::detail::vertex_property_map<boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>, boost::vertex_index_t>'
/usr/include/boost/graph/properties.hpp:212:10: required from 'struct boost::property_map<boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>, boost::vertex_index_t, void>'
/usr/include/boost/graph/detail/adjacency_list.hpp:1733:5: required by substitution of 'template<class Config, class Base, class Property> typename boost::property_map<typename Config::graph_type, Property>::const_type boost::get(Property, const boost::adj_list_helper<Config, Base>&) [with Config = boost::detail::adj_list_gen<boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>, boost::setS, boost::setS, boost::undirectedS, int, float, boost::no_property, boost::listS>::config; Base = boost::undirected_graph_helper<boost::detail::adj_list_gen<boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>, boost::setS, boost::setS, boost::undirectedS, int, float, boost::no_property, boost::listS>::config>; Property = boost::vertex_index_t]'
/usr/include/boost/graph/copy.hpp:353:38: required from 'void boost::copy_graph(const VertexListGraph&, MutableGraph&) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>; MutableGraph = boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, int, float>]'
/my/file/and/line/num: required from here
/usr/include/boost/graph/detail/adjacency_list.hpp:2543:29: error: forming reference to void
typedef value_type& reference;
^~~~~~~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2544:35: error: forming reference to void
typedef const value_type& const_reference;
^~~~~~~~~~~~~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2547:47: error: forming reference to void
<Graph, value_type, reference, Tag> type;
^~~~
/usr/include/boost/graph/detail/adjacency_list.hpp:2549:53: error: forming reference to void
<Graph, value_type, const_reference, Tag> const_type;
^~~~~~~~~~
...

In file included from/my/file:5:0:
/usr/include/boost/graph/copy.hpp: In instantiation of 'void boost::copy_graph(const VertexListGraph&, MutableGraph&) [with VertexListGraph = boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>; MutableGraph = boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, int, float>]':
/my/file/and/line/num: required from here
/usr/include/boost/graph/copy.hpp:353:38: error: no matching function for call to 'get(boost::vertex_index_t, const boost::adjacency_list<boost::setS, boost::setS, boost::undirectedS, int, float>&)'
get(vertex_index, g_in), orig2copy[0]),
~~~^~~~~~~~~~~~~~~~~~~~

Answer

The vertex map is not specified. It's easy to create one:

std::map<AdjacencyList::vertex_descriptor, int> index;
for (auto v : boost::make_iterator_range(boost::vertices(adj))) {
    index.insert(std::make_pair(v, index.size()));
}

AdjacencyListWithVec adj_vec;
boost::copy_graph(adj, adj_vec, boost::vertex_index_map(boost::make_assoc_property_map(index)));