Re: [Boost-users] [BGL] Writing an edge_iterator for add_edges in CSR graph

On Fri, 8 Apr 2011, Johan Oudinet wrote:

On Fri, Apr 8, 2011 at 1:50 PM, Johan Oudinet wrote:

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Hi,

I'm trying to write an edge_iterator in order to load a CSR graph from a GraphViz by using the add_edges method.

Could you use one of the iterator-based constructors instead of add_edges?

...

So far, I successfully write a edge_iterator so you can iterate on it and dereference it to get either a pair of vertex_descriptor or a edge label.

However, if it try to use this iterator as arguments for the method add_edges of CSR graph, I got cryptic errors and I don't know how to solve them :-/

Problem solved. My input_iterator must be copy constructible and was not due to the std::ifstream attribute. Now, I use a boost::shared_ptr and it solves the compilation errors.

Thanks anyway.

P.S.: It could be a good idea to add an example in CSR documentation that uses this new add_edges method instead of the old add_edge method, which is more difficult to use I think.

P.P.S.: Do you plan to adapt the Graphviz reader in order to load CSR graphs?

I didn't realize it was broken, but it doesn't seem too hard to fix (sort the edges and use add_edges to put them into the graph when possible). Could you please file a bug report for that? For now, you can need to read the graph into an adjacency_list and then copy it from there to CSR. You won't need custom iterators for that copy (there is a CSR constructor from arbitrary graphs). -- Jeremiah Willcock