Re: [boost] [BGL] To customize the graph traversing

Subject: Re: [boost] [BGL] To customize the graph traversing
From: Dmitry Bufistov (dmitry_at_[hidden])
Date: 2009-07-15 09:40:10

Cosimo Calabrese wrote:
> 
>>
>> You also may try to use filtered graph adaptor
>> http://www.boost.org/doc/libs/1_39_0/libs/graph/doc/filtered_graph.html
>>
> 
> 
> Thank you Dmitry,
> 
> but I can't use the filtered graph, because it completely hides edges; 
> instead I would to hide an edge if I "come" from a particulary adjacent 
> edge, and to show an edge if I come from another adjacent edge. In this 
> other graph (I hope it's comprehensible...):

You graph drawing  is very nice :-)
> 
> 
>          _C       _F
>          o|       /|
>         o        /
>        o        /
> A---->B------> D o o o >G
>        \       ^ \
>         \      |  \
>         _\|    |  _\|
>           E    |    H
>                I
> 
> if the exploration goes through AB, and then BD, I can't go in DG, but 
> only in DF and DH; instead if I come from ID, so I can go in DG.
> 
> It is an exploration problem. I think that a Dijkstra/BFS foundation is 
> that the graph must be immutable during the exploration. Instead I would 
>  to hide the DG edge in some cases, and to show it in other cases.
> 
> 
> Best regards,
> Cosimo Calabrese.
> 

Yep. I see now. Sorry.
What if you just "unfold" you graph to explicitly create all possible 
paths? For example, in your example you should duplicate node D to D1 
and D2 and remove edge (D2->G):

          _C       _ F
          o|       //|\
         o        / /
        o        / /
A---->B------> D1/o o o >G
       |         /\
       \        D2 \
        \       ^ \ \
         \      |  \ \
         _\|    |  _\||/
           E    |    H
                I

Regards,
Dmitry