copy a graph (adjacency_list) to another one

Question

How can I copy a graph of type adjacency_list to another one graph of type adjacency_list ?

typedef adjacency_list<setS, setS, undirectedS, NodeDataStruct, EdgeDataStruct> MyGraph;
MyGraph g1, g2;

// processing g1: adding vertices and edges ...
// processing g2: adding some vertices and edges ...

g1.clear();
g1 = g2 // this gives an execution error (exception)
g1 = MyGraph(g2); // this also gives an execution error
g2.clear();

Answer 1

Have you tried copy_graph ?

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Hard to know what the problem is without seeing the errors but if I had to guess, I'd first make sure you're providing a vertex_index map to copy_graph since it's not available by default when you use setS for vertex storage. Based on your earlier question , it looks like you've already got that figured out so we just need to bring it all together.

  typedef adjacency_list<setS, setS, undirectedS, NodeDataStruct, EdgeDataStruct> MyGraph;
  typedef MyGraph::vertex_descriptor NodeID;

  typedef map<NodeID, size_t> IndexMap;
  IndexMap mapIndex;
  associative_property_map<IndexMap> propmapIndex(mapIndex);

  MyGraph g1, g2;

  // processing g1: adding vertices and edges ...
  // processing g2: adding some vertices and edges ...

  int i=0;
  BGL_FORALL_VERTICES(v, g2, MyGraph)
  {
     put(propmapIndex, v, i++);
  }

  g1.clear();
  copy_graph( g2, g1, vertex_index_map( propmapIndex ) );
  g2.clear();