Re: [Boost-users] graph cut compilation error

Subject: Re: [Boost-users] graph cut compilation error
From: David Doria (daviddoria+boost_at_[hidden])
Date: 2009-09-08 14:42:35

On Tue, Sep 8, 2009 at 1:17 PM, Jeremiah Willcock <jewillco_at_[hidden]>wrote:

> On Tue, 8 Sep 2009, David Doria wrote:
>
>  I made a super simple example: A graph with 2 nodes and an edge between
>> them. On trying to call kolmogorov_max_flow, I am getting:
>> error: cannot convert 'boost::detail::error_property_not_found' to 'long
>> int' in initialization
>>
>
> You are missing the edge weights and other property maps described in the
> documentation for kolmogorov_max_flow; you can supply them either as
> parameters to the kolmogorov_max_flow function or as particular property
> maps in your graph.  You can add properties as template parameters to the
> adjacency_list class (see the documentation for how to do that), or use
> external properties.  Once you have properties, you can use add_edge(source,
> target, prop, g) to add edges with properties.
>
> -- Jeremiah Willcock
> __

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;
}

Thanks,

David