[Boost-users] Custom Edge Properties (boost-graph) - struct

[Kya Bey]

Hi All , 

I've been trying to use a custom structure for describing the various edge properties of a graph. I'm defining a graph as the following

struct edge_properties {

    int         capacity ; 

    double      weight ;

    typedef struct edge_properties_tag kind ;  // NOT SURE what this does ? 

};

typedef boost::adjacency_list<listS, vecS, bidirectionalS,

                              property<vertex_name_t, std::string>,

                              edge_properties > Graph;

This allows me to create a Graph instance g. I've been trying to retrieve the edge properties via a get call, but have not been able to do so. 

To retrieve the vertex properties doing the following works 

property_map<Graph, vertex_name_t>::type  v_names ; 

v_names = get(vertex_name,g) ; 

But on attempting to do something similar for retrieving the edge properties always fails with the following error message 

"test.cpp: 75: error: expected primary-expression before ',' token"

test.cpp

71: property_map<Graph, edge_properties>::type    epr;

72: property_map<Graph, vertex_name_t>::type  v_names ; 

74: v_names = get(vertex_name,g) ; 

75:  epr = get(edge_properties,g) ; 

I've tried various variants but seems to me i'm missing something fundamental in the way boost-graph keeps the edge_properties hidden. 

Any pointers will be useful. 

Thanks in advance

[Kya Bey]

[Steven Watanabe]

AMDG

Kya Bey wrote:
> property_map<Graph, vertex_name_t>::type v_names ;
> v_names = get(vertex_name,g) ;
>
> But on attempting to do something similar for retrieving the edge properties
> always fails with the following error message
>
> "test.cpp: 75: error: expected primary-expression before ',' token"
>
> test.cpp
>
> 71: property_map<Graph, edge_properties>::type epr;
> 72: property_map<Graph, vertex_name_t>::type v_names ;
>
> 74: v_names = get(vertex_name,g) ;
> 75: epr = get(edge_properties,g) ;
>

edge_properties appears to be a type, not an object here.

> I've tried various variants but seems to me i'm missing something
> fundamental in the way boost-graph keeps the edge_properties hidden.
> Any pointers will be useful.
>

In Christ,
Steven Watanabe

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[Jeremiah Willcock]

On Sun, 14 Mar 2010, Kya Bey wrote:

> Hi All ,�
> I've been trying to use a custom structure for describing the various edge properties of a graph. I'm defining a graph as the following
>
> struct edge_properties�{
> �� �int � � � � capacity ;�
> �� �double � � �weight ;
> �� �typedef struct edge_properties_tag kind ; �// NOT SURE what this does ?�
> };
>
> typedef boost::adjacency_list<listS, vecS, bidirectionalS,
> �� � � � � � � � � � � � � � �property<vertex_name_t, std::string>,
> �� � � � � � � � � � � � � � �edge_properties > Graph;
>
>
> This allows me to create a Graph instance g. I've been trying to retrieve the edge properties via a get call, but have not been able to

> do so.�

It appears that you are trying to use bundled properties. There is
information on using them at
<URL:http://www.boost.org/doc/libs/1_42_0/libs/graph/doc/bundles.html>.
You do not need the kind in your structure in that case.

> I've tried various variants but seems to me i'm missing something fundamental in the way boost-graph keeps the edge_properties hidden.�

> Any pointers will be useful.�

The syntax you want is get(&edge_properties::capacity, g) to get the
capacity, and something similar for the weight.

-- Jeremiah Willcock

[Kya Bey]

Thanks a lot for your pointers. It helped me a lot. I'm stuck at getting dijkstra's to work (posting in another thread)