[Graph] I could not get the reversed graph!
HI, All, I could not get a instance of reversed graph by calling make_reverse_graph(g). That is, I have following type: typedef adjacency_list< listS, listS, bidirectionalS, property<vertex_index_t, std::size_t>, no_property> G; typedef reverse_graph<G, G&> ReverseG; //Maybe something wrong here. After I call make_revserse_graph(G) as following, I could not get a instance of modified graph by accessing some fields of ReverseG. ReverseG tmp=boost::make_reverse_graph(g); //I try to get the reservsed graph here. The only field is tmp.m_g, which is G& type and the original graph, but is not the reversed graph. Thanks. Jiangfan
On Fri, 2007-07-06 at 13:17 -0500, jiangfan shi wrote:
The reverse_graph class template in the BGL is a reversed *view* of the existing graph. It costs essentially nothing to build this view, but when you look at the reverse_graph of a graph you see all of its edges going backwards (the actual storage in the graph is unchanged). Because it's a view, changes to the original graph will show up immediately in the reversed graph. - Doug
Thanks, Doug,
The reverse_graph class template in the BGL is a reversed *view* of the existing graph.
So I have to build the "real" reversed graph by myself, or change the "original" graph to build up the reversed graph. The reason is that I want to use such reversed instance to get the dominator tree. Jiangfan
On Fri, 2007-07-06 at 14:32 -0500, jiangfan shi wrote:
Most likely, you don't need to build the reversed graph. You can just run algorithms on the reversed "view" of the original graph: that's exactly what the reverse_graph adaptor is meant for. For example, you can call: lengauer_tarjan_dominator_tree(make_reverse_graph(graph), exit_node, dominators) - Doug
Thanks, Doug,
make_reverse_graph(graph) does not give me the G type (defined in the following code), so I could not use it in this way. This is the reason I use the following code which does not work. typedef adjacency_list< listS, listS, bidirectionalS, property<vertex_index_t, std::size_t>, no_property> G; typedef reverse_graph<G, G&> ReverseG; ReverseG g2=boost::make_reverse_graph(g); ... lengauer_tarjan_dominator_tree(g2.m_g, vertex(0, g), domTreePredMap); Jiangfan
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Douglas Gregor -
jiangfan shi