Hello Everybody! I am trying to extract a part of a graph. Speaking in terms of the BGL, I do a copy from a filtered graph object into a new graph. To do so, I defined a VerticePredicate for the filtered graph. As a result not all vertices in the graph are present in the filtered version. This implies that some edges do disappear in the filtered version fo the graph. In order to copy from this filtered graph into a new, fresh graph via copy, do I have to use the following EdgePredicate? // edge predicate which only lets edges through which are part // of the given VerticePredicate template <class Graph, class VerticePredicate> struct edge_filter { typedef boost::graph_traits<Graph> Traits; typedef typename Traits::edge_descriptor Edge; // needs to be default-constructible ! edge_filter() { } edge_filter(Graph& g, VerticePredicate& vFilter) : m_g(&g), m_vFilter(&vFilter) {} bool operator()(const Edge& e) const { return (*m_vFilter)(boost::target(e,*m_g)) && (*m_vFilter)(boost::source(e,*m_g)); } private: Graph* m_g; VerticePredicate* m_vFilter; }; Or is this not necessary and implicitly done by the filtered graph interface? Another thing concernig the copy-function: Is there a way to NOT copy the vertice indices, but rather have the vertices renumbered from 1 to size of filtered graph? I guess I have to cope with the vertice_copier-function stuff, but I don't see how to do it. And another matter: The copy_component function does not seem to be documented. I found it by chance in the sources of copy.hpp. Thanks a lot! Sebastian Weber
On Apr 28, 2005, at 5:39 AM, Sebastian Weber wrote:
Hello Everybody!
I am trying to extract a part of a graph. Speaking in terms of the BGL, I do a copy from a filtered graph object into a new graph. To do so, I defined a VerticePredicate for the filtered graph. As a result not all vertices in the graph are present in the filtered version. This implies that some edges do disappear in the filtered version fo the graph. In order to copy from this filtered graph into a new, fresh graph via copy, do I have to use the following EdgePredicate? [snip predicate that also checks vertex] Or is this not necessary and implicitly done by the filtered graph interface?
The filtered graph already does this for you.
Another thing concernig the copy-function: Is there a way to NOT copy the vertice indices, but rather have the vertices renumbered from 1 to size of filtered graph? I guess I have to cope with the vertice_copier-function stuff, but I don't see how to do it.
If you are referring to copying the vertex_index property, you're probably better off just renumbering vertices at the end.
And another matter: The copy_component function does not seem to be documented. I found it by chance in the sources of copy.hpp.
I've never even heard of this function :) It does look useful... adding it to the list o' bugs, and we'll try to get to it soon. Doug
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Douglas Gregor -
Sebastian Weber