[Lemon-user] GraphCopy - directed vs. undirected

[Balazs Dezso]

Hi,

I could make directed copy of undirected graph, my code is the following:
#include <lemon/smart_graph.h>
#include <lemon/lgf_writer.h>

using namespace lemon;

int main(int argc, const char *argv[]) {
  SmartDigraph target;
  SmartDigraph::ArcMap<int> tmap(target);

  SmartGraph source;
  SmartGraph::Node n1 = source.addNode();
  SmartGraph::Node n2 = source.addNode();
  SmartGraph::Edge e = source.addEdge(n1, n2);
  SmartGraph::EdgeMap<int> map(source);
  map[e] = 42;

  digraphCopy(source, target).arcMap(map, tmap).run();

  digraphWriter(target, std::cout).arcMap("map", tmap).run();
  
  return 0;
}

I think, the order of source and destination graphs in the parameter list are 
changed in 1.x versions. Because each undirected graph is at the same time 
directed graph, therefore you can use digraphCopy().

Best regards, Balazs


On Tuesday 02 February 2010 21:02:24 Mitcsenkov Attila wrote:
> Hi,
> 
> I would like to create a directed copy of an undirected graph.
> More detailed: I have a ListGraph instance, and based on that I want to
>  create a directed graph, with two directed arcs instead of any undirected
>  edge, with some edgemap values "duplicated", e.g. if length[e] was 5 in
>  the undirected graph, I want to have two directed arcs, both with length
>  5.
> 
> Once I was using Lemon 0.x, it was working by using graphcopy.
> 
> Now I cannot solve the problem, since the GraphCopy and DigraphCopy needs
>  two undirected or two directed graphs. I have tried to use the
>  Orienter/Undirector adaptors, but with those I have the following error
>  messages:
> 
> 3>.\OptimalLP.cpp(52) : error C2664:
>  'lemon::DigraphCopy<From,To>::DigraphCopy(const From &,To &)' : cannot
>  convert parameter 1 from 'lemon::Orienter<GR,DM>' to 'const
>  lemon::ListDigraph &' 3>        with
> 3>        [
> 3>            From=lemon::ListDigraph,
> 3>            To=lemon::ListDigraph
> 3>        ]
> 3>        and
> 3>        [
> 3>            GR=const lemon::ListGraph,
> 3>            DM=const
>  lemon::GraphExtender<lemon::ListGraphBase>::EdgeMap<bool> 3>        ]
> 3>        Reason: cannot convert from 'lemon::Orienter<GR,DM>' to 'const
>  lemon::ListDigraph' 3>        with
> 3>        [
> 3>            GR=const lemon::ListGraph,
> 3>            DM=const
>  lemon::GraphExtender<lemon::ListGraphBase>::EdgeMap<bool> 3>        ]
> 3>        No user-defined-conversion operator available that can perform
>  this conversion, or the operator cannot be called
> 
> As far as I understand the concept of graph adaptors, it should be
>  available to use instead of ListDigraph...
> 
> Could you please help to solve this?
> 
> Thanks:
> Attila Mitcsenkov
>