Re: [Boost-users] Trouble w/ fruchterman-reingold

On Thu, 4 Oct 2012, eric wrote:

Wow, okay ... thank you. I have to admit that this is all a little bit of voodoo for me. There are a lot of things going on behind the scenes that I don't understand.

I'm trying to get my toy prototype into what I need it to be, but as soon as I switch from defining my Vertex this way:

typedef property

...

Vertex;

to defining it this way:

struct Vertex { int property1; int property2; };

I start getting this compiler error:

1>c:\program files (x86)\boost\boost_1_51\boost\graph\detail\adjacency_list.hpp(2540) : error C2039: 'type' : is not a member of 'boost::property_value' 1> with 1> [ 1> PropertyList=wmain::Vertex, 1> Tag=int 1> ]

That comes from "struct vec_adj_list_any_vertex_pa", which I assume is the vector adjacency_list vertex property ... accessor? Anyway, I don't know how to get my property_value to have a "::type" ... or where the property_value comes from in the first place, for that matter.

property_value is a traits class that looks up the type information about a property map. I don't know why Tag is set to "int"; it would usually have the name of the property map that is not being found (likely vertex_index_t in your case). That might be elsewhere in the instantiation stack, though.

Could you help me understand? Or if there is something I could read that would clear it all up for me, that would be awesome, too. I trolled through the docs, but haven't hit on something that makes me understand what is going on.

I don't know if there is a good explanation now, but since you changed the definition of Vertex, you are no longer providing a vertex_index_t property map (assuming you are using listS as vertex container), and so you'll need to provide either that or a displacement map to fruchterman_reingold as an explicit argument. See the vertex_index_map part of http://www.boost.org/doc/libs/1_51_0/libs/graph/doc/fruchterman_reingold.htm... for how to pass a custom vertex index map to the algorithm. -- Jeremiah Willcock