Re: [Boost-users] [boost] [Graph] need help on remove_vertex ....

From: Aaron Windsor (aaron.windsor_at_[hidden])
Date: 2008-03-26 09:06:19

On Sun, Mar 23, 2008 at 6:21 PM, Bernhard Lippmann
<bernhard.lippmann_at_[hidden]> wrote:
>
>  Hi,
>
>
>  I need some help on the remove_edge, remove_vertex functions.
>  What is wrong with my two  functions, removing edges or vertex from a graph
>  with a given name in the coressponding property map.
>  pls. see code snippet
>  after calling my function a second time I get a run time error.
>  I did the code as shown under
>  http://www.boost.org/libs/graph/doc/adjacency_list.html
>  but I feel the rebuild of the vectors did not work,
>  any input is welcome
>
>  Best
>
>  Bernhard
>
>
>
>
>
>  this is the code in the main program:
>
>    //  ok
>     MyElementList.RemoveVertexByName("vss!",g, VertexNamesMap);
>   //   now the run time error ...
>     MyElementList.RemoveVertexByName("vss!s",g, VertexNamesMap);
>
>
>
>  this is the called sub routine:
>
>
>
>  /*$
>  ****************************************************************************
>  **
>                                         Method Name                     RemoveVertexByName ()...
>                                         Parameters                      std::string AE_Name
>                                         Return                          long  , Index in Map
>                                         Description                     remove vertex with a given name
>                                                             see
>  http://www.boost.org/libs/graph/doc/adjacency_list.html
>                                                                                 for troubles
>  ****************************************************************************
>  ****** */
>  void  TElementList::RemoveVertexByName(std::string elementname, TGraph   &g,
>  TVertexNameMap   &VertexNamesMap)
>  {
>   Tvertex_iter vi, vi_end, next;
>   tie(vi, vi_end) = vertices(g);
>   for (next = vi; vi != vi_end; vi = next) {
>     ++next;
>         if (VertexNamesMap[*vi] == elementname) {
>                 remove_vertex(*vi, g); }
>   }
>
>  }

Hi Bernhard,

Your RemoveVertexByName function will work only if the vertices in
your graph are stored in a list, but your email seems to suggest that
you have them stored in a vector. If your vertices are stored in a
vector, you're not going to be able to remove them in a single loop
like this because you'll invalidate the underlying std::vector
iterators you're using when you remove vertices. If you are using a
list to store your vertices, this code should work as long as
VertexNamesMap is populated with all of the vertices in your original
graph.

Regards,
Aaron