public void IterativelySwapEdgesToIncreaseAssortativity()
{
var edges = EdgesAsNodes.OrderBy(e => LocalAssort(e)).ToList();
while (edges.Count > 1)
{
var e1 = edges[0];
edges.Remove(e1);
var otherEdges =
edges.Where(
e2 =>
e1.Item1 != e2.Item1 &&
e1.Item1 != e2.Item2 &&
e1.Item2 != e2.Item1 &&
e1.Item2 != e2.Item2).ToList();
var currVal = LocalAssort(e1);
var currMaxImprovement = 0.0;
Tuple <Node, Node> currMaxEdge = null;
EdgeSwap bestEdgeSwap = EdgeSwap.e1Ae2A_e1Be2B; // just need to assign something..
foreach (var e2 in otherEdges)
{
double improvement;
if (!e1.Item1.Neighbors.Contains(e2.Item1) && !e1.Item2.Neighbors.Contains(e2.Item2))
{
improvement = (LocalAssort(new Tuple <Node, Node>(e1.Item1, e2.Item1)) +
LocalAssort(new Tuple <Node, Node>(e1.Item2, e2.Item2))) /
2.0 - currVal;
if (improvement > currMaxImprovement)
{
currMaxImprovement = improvement;
currMaxEdge = e2;
bestEdgeSwap = EdgeSwap.e1Ae2A_e1Be2B;
}
}
if (!e1.Item1.Neighbors.Contains(e2.Item2) && !e1.Item2.Neighbors.Contains(e2.Item1))
{
improvement = (LocalAssort(new Tuple <Node, Node>(e1.Item1, e2.Item2)) +
LocalAssort(new Tuple <Node, Node>(e1.Item2, e2.Item1))) /
2.0 - currVal;
if (improvement > currMaxImprovement)
{
currMaxImprovement = improvement;
currMaxEdge = e2;
bestEdgeSwap = EdgeSwap.e1Ae2B_e1Be2A;
}
}
}
if (currMaxEdge != null)
{
if (bestEdgeSwap == EdgeSwap.e1Ae2A_e1Be2B)
{
AddEdge(e1.Item1, currMaxEdge.Item1);
AddEdge(e1.Item2, currMaxEdge.Item2);
}
else
{
AddEdge(e1.Item1, currMaxEdge.Item2);
AddEdge(e1.Item2, currMaxEdge.Item1);
}
RemoveEdge(e1.Item1, e1.Item2);
RemoveEdge(currMaxEdge.Item1, currMaxEdge.Item2);
edges.Remove(currMaxEdge);
}
}
}
