Re: [Boost-users] graph library : isomorphism.hpp vertex invariant parameter

On 6/12/07, Patrick A. La Fratta wrote:

Setting the "vertex_invariant" parameter to the isomorphism function does not seem to have any affect on the behavior of the function. In isomorphism.hpp, it appears that the function "isomorphism_impl" is supposed to read the parameter at the return statement:

return isomorphism(G1, G2, f, choose_param(get_param(params, vertex_invariant1_t()), invariant1), choose_param(get_param(params, vertex_invariant2_t()), invariant2), choose_param(get_param(params, vertex_max_invariant_t()), ( invariant2.max)()), index_map1, index_map2 );

If "vertex_invariant1_t()" and "vertex_invariant2_t()" are both changed to "vertex_invariant_t()", the setting of the parameter then seems to have an affect. Has anyone been able to successfully set the vertex_invariant parameter using the named parameter version of the isomorphism function? I have had to resort to calling one of the internal isomorphism functions to set this parameter.

any help is appreciated, Patrick

Hi Patrick, It appears that the algorithm implementation diverged a little from the documentation. The docs mention a "vertex_invariant" named parameter whose operator() must work on both graphs passed in to the isomorphism function - this was later replaced with two separate vertex invariant functors - "vertex_invariant1" and "vertex_invariant2", which could be applied to the first and second input graph, respectively. You're right, though, the named parameter mechanism wasn't fully set up to handle this when this change was made. If you'd like, use the diff I've appended to this email to patch the file boost/graph/named_params.hpp. This patch just adds some necessary definitions so that you can actually use vertex_invariant1 and vertex_invariant2 as named parameters in the function, like so: MyVertexInvariant1 my_invariant1; MyVertexInvariant2 my_invariant2; bool are_isomorphic = isomorphism(g1,g2, isomorphism_map(my_isomorphism_map) .vertex_index1_map(my_vertex_index_map1) .vertex_index2_map(my_vertex_index_map2) .vertex_invariant1(my_invariant1) .vertex_invariant2(my_invariant2)); Does anyone object if I commit this patch to HEAD and update the documentation for isomorphism to reflect the two separate vertex invariant named parameters? Regards, Aaron ---------------------------------------------------------------------------------------------------------- 286a287,300

template <typename VertexInvar> bgl_named_params vertex_invariant1(const VertexInvar& c) const { typedef bgl_named_params Params; return Params(c, *this); }

template <typename VertexInvar> bgl_named_params vertex_invariant2(const VertexInvar& c) const { typedef bgl_named_params Params; return Params(c, *this); }

549a564,577

template <typename VertexInvar> bgl_named_params vertex_invariant1(const VertexInvar& c) { typedef bgl_named_params Params; return Params(c); }

template <typename VertexInvar> bgl_named_params vertex_invariant2(const VertexInvar& c) { typedef bgl_named_params Params; return Params(c); }