Hi!
I am using a graph with setS as EdgeList template-parameter.
I currently try to implement to get the number of neighbors which two
vertices have in common.
I tried to solve this problem by walking thought both out_edge_iterator -
ranges in parallel.
tie( i, i_end ) = out_edges( vertex_i, graph );
tie( j, j_end ) = out_edges( vertex_j, graph );
int a =0;
for( ;; )
{
if( *i == *j )
{
++i;
++j;
++a;
if( i == iend ) return a;
if( j == jend ) return a;
} else if( *i < *j ) { // PROBLEM
++i;
if( i == iend ) return a;
} else /* ( *i > *j ) */ {
++j;
if( j == jend ) return a;
};
};
return 0;
};
And get the following error message:
../../../pocket_graph/src/clustering/GraphAssociation.h:147: error: no
match
for 'operator<' in 'boost::iterator_facade::operator*()
const [with Derived =
Which basicaly tells me that operator< is not defined for an edge
descriptor.
After digging through some bgl-code I found the class stored_edge (in
detail/adjacency_list.hpp )
template <class Vertex>
class stored_edge
: public boost::equality_comparable1< stored_edge<Vertex>,
boost::less_than_comparable1< stored_edge<Vertex> > >
{
public:
typedef no_property property_type;
inline stored_edge() { }
inline stored_edge(Vertex target, const no_property& =
no_property())
: m_target(target) { }
// Need to write this explicitly so stored_edge_property can
// invoke Base::operator= (at least, for SGI MIPSPro compiler)
inline stored_edge& operator=(const stored_edge& x) {
m_target = x.m_target;
return *this;
}
inline Vertex& get_target() const { return m_target; }
inline const no_property& get_property() const { return s_prop; }
inline bool operator==(const stored_edge& x) const
{ return m_target == x.get_target(); }
inline bool operator<(const stored_edge& x) const
{ return m_target < x.get_target(); }
//protected: need to add hash<> as a friend
static no_property s_prop;
// Sometimes target not used as key in the set, and in that case
// it is ok to change the target.
mutable Vertex m_target;
};
for some reason I can not use operator<() or get_target(), but accessing
m_target directly works (cause its mutable???)...
} else if( i->m_target < j->m_target ) { // SOLUTION ?!
However - I feel a bit uneasy to use such a low level interface... Does
anyone know of a better solution?
Thanks for your help!
Lars
