Re: [Boost-users] graph cut compilation error

Subject: Re: [Boost-users] graph cut compilation error
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2009-09-09 10:50:30

> Jeremiah,
> 
> Thanks for the response. I am very new to boost, so I am not quite getting the Property Map idea.
> It seems like you can just provide a whole list of template arguments that are of type property<> to the adjacency_list
> object. It the kolmogorov example (http://www.boost.org/doc/libs/1_39_0/libs/graph/doc/kolmogorov_max_flow.html) , it looks
> like the only property that is needed is edge_capacity, so I defined EdgeCapacityProperty (it was actually quite a
> complicated property, depending on edge_reverse as well as edge_residual_capacity).  However, I am still getting "conversion
> from error_property_not_found to EdgeCapacityProperty requested" when I try to call the maxflow function. Is this getting
> closer?
> 
> I guess I am following the property<> stuff, but not the property_map<> idea? Here is the latest attempt:
> 
> #include <iostream>                  // for std::cout
> #include <boost/graph/adjacency_list.hpp>
> #include <boost/graph/kolmogorov_max_flow.hpp>
> 
> using namespace boost;
> 
> typedef adjacency_list_traits<vecS, vecS, bidirectionalS> Traits;
> 
> typedef property<edge_reverse_t, Traits::edge_descriptor> EdgeReverseProperty;
> typedef property<edge_residual_capacity_t, long, EdgeReverseProperty> EdgeResidualCapacityProperty;
> typedef property<edge_capacity_t, double, EdgeResidualCapacityProperty> EdgeCapacityProperty;
> 
> typedef adjacency_list<vecS, vecS, bidirectionalS, EdgeCapacityProperty> Graph; //simple
> 
> int main(int,char*[])
> {
>    // declare a graph object
>     Graph g(2); //a graph with 2 vertices
>
>     //add an edge between node 0 and node 1 with weight (capacity) 2.3
>     EdgeCapacityProperty e = 2.3;
>     add_edge(0, 1, e, g);
>
>     //find min cut
>
>     Traits::vertex_descriptor s, t;
>     //double flow = kolmogorov_max_flow(g, s, t); // a list of sources will be returned in s, and a list of sinks will be
> returned in t
>     EdgeCapacityProperty flow = kolmogorov_max_flow(g, s, t); // a list of sources will be returned in s, and a list of
> sinks will be returned in t
>     std::cout << "Max flow is: " << flow << std::endl;
>
>     return 0;
> }

Sorry -- I tried your code and the problem is not a missing property map 
at all.  Your code on line 28 converts from a double to an 
EdgeCapacityProperty, which is a boost::property.  I do not see what the 
four-argument add_edge's property should be, so just get the result from 
"add_edge(0, 1, g).first" as e and then do "put(edge_capacity, g, e, 
2.3)" or similar to write properties.

-- Jeremiah Willcock