private void OnVertexDiscovered([NotNull] TVertex vertex)
{
Debug.Assert(vertex != null);
VisitedGraph.AddVertex(vertex);
_unExploredVertices.Enqueue(vertex);
DiscoverVertex?.Invoke(vertex);
}
/// <inheritdoc />
protected override void InternalCompute()
{
foreach (DataTable table in DataSet.Tables)
{
VisitedGraph.AddVertex(table);
}
foreach (DataRelation relation in DataSet.Relations)
{
VisitedGraph.AddEdge(new DataRelationEdge(relation));
}
}
/// <inheritdoc />
protected override void InternalCompute()
{
if (Augmented)
{
throw new InvalidOperationException("Graph already augmented.");
}
SuperSource = VertexFactory();
VisitedGraph.AddVertex(SuperSource);
OnSuperSourceAdded(SuperSource);
SuperSink = VertexFactory();
VisitedGraph.AddVertex(SuperSink);
OnSuperSinkAdded(SuperSink);
AugmentGraph();
Augmented = true;
}
/// <summary>
/// Runs the graph balancing algorithm.
/// </summary>
/// <exception cref="InvalidOperationException">If the graph is already balanced.</exception>
public void Balance()
{
if (Balanced)
{
throw new InvalidOperationException("Graph already balanced.");
}
// Step 0
// Create new balancing source and sink
BalancingSource = VertexFactory();
VisitedGraph.AddVertex(BalancingSource);
OnBalancingSourceAdded();
BalancingSink = VertexFactory();
VisitedGraph.AddVertex(BalancingSink);
OnBalancingSinkAdded();
// Step 1
// Link balancing source to the flow source
BalancingSourceEdge = EdgeFactory(BalancingSource, Source);
VisitedGraph.AddEdge(BalancingSourceEdge);
Capacities.Add(BalancingSourceEdge, double.MaxValue);
_preFlow.Add(BalancingSourceEdge, 0);
OnEdgeAdded(BalancingSourceEdge);
// Link the flow sink to the balancing sink
BalancingSinkEdge = EdgeFactory(Sink, BalancingSink);
VisitedGraph.AddEdge(BalancingSinkEdge);
Capacities.Add(BalancingSinkEdge, double.MaxValue);
_preFlow.Add(BalancingSinkEdge, 0);
OnEdgeAdded(BalancingSinkEdge);
// Step 2
// For each surplus vertex v, add (source -> v)
foreach (TVertex vertex in VisitedGraph.Vertices.Where(v => !IsSourceOrSink(v)))
{
int balancingIndex = GetBalancingIndex(vertex);
if (balancingIndex == 0)
{
continue;
}
if (balancingIndex < 0)
{
// Surplus vertex
TEdge edge = EdgeFactory(BalancingSource, vertex);
VisitedGraph.AddEdge(edge);
_surplusEdges.Add(edge);
_surplusVertices.Add(vertex);
_preFlow.Add(edge, 0);
Capacities.Add(edge, -balancingIndex);
OnSurplusVertexAdded(vertex);
OnEdgeAdded(edge);
}
else
{
// Deficient vertex
TEdge edge = EdgeFactory(vertex, BalancingSink);
_deficientEdges.Add(edge);
_deficientVertices.Add(vertex);
_preFlow.Add(edge, 0);
Capacities.Add(edge, balancingIndex);
OnDeficientVertexAdded(vertex);
OnEdgeAdded(edge);
}
}
Balanced = true;
#region Local function
bool IsSourceOrSink(TVertex v)
{
return(v.Equals(BalancingSource) ||
v.Equals(BalancingSink) ||
v.Equals(Source) ||
v.Equals(Sink));
}
#endregion
}
