/**
* Augments the path the vertex
*
* @param g the {@link Graph}
* @param v the {@link Vertex} to start from
* @param pred a {@link VertexArray}
*/
private void augmentPathTo(Graph g, Vertex v, final VertexArray pred) {
Edge e = (Edge) pred.getVertexProperty(v);
while (e != null) {
e.turnOverEdgeDirection();
e = (Edge) pred.getVertexProperty(GraphUtilities.getEdgeTargetVertex(g, e));
}
}
/** Release resources */
public void nullify() {
try {
g = null;
c.nullify();
c = null;
pot.nullify();
pot = null;
} catch (NullPointerException e) {
}
}
/**
* Run the algorithm
*
* @return an {@link EdgesSet}
*/
public EdgesSet runAlgorithm() {
EdgesSet result = new EdgesSet(g.getEdgesSet().getVc());
// for all nodes(v,G) pot[v] = 0;
// this will be done by giving pot:= VertexArray(g,new Double(0))
if (g.getEdgesSet().isEmpty()) return new EdgesSet(g.getEdgesSet().getVc());
// check that all edges are directed from A to B
// this should be a precondition also
VertexArray free = new VertexArray(g, new Boolean(true));
VertexArray pred = new VertexArray(g, null);
VertexArray dist = new VertexArray(g, new Double(0));
VertexPQ PQ = new VertexPQ(g);
switch (heuristic) {
case NAIVE_HEURISTIC:
Double C = new Double(0);
Iterator<Edge> edgesIterator = g.getEdgesIterator();
while (edgesIterator.hasNext()) {
Edge e = edgesIterator.next();
Double edgeC = (Double) c.getEdgeProperty(e);
if (edgeC.compareTo(C) == 1) // bigger than...
C = edgeC;
}
Iterator<Vertex> leftVertexesIterator = g.getLeftVertexSetIterator();
while (leftVertexesIterator.hasNext()) {
pot.setVertexProperty(leftVertexesIterator.next(), C);
}
break;
case SIMPLE_HEURISTIC:
Iterator<Vertex> leftVertexesIterator1 = g.getLeftVertexSetIterator();
while (leftVertexesIterator1.hasNext()) {
Vertex a = leftVertexesIterator1.next();
Edge eMax = null;
double C_max = 0;
Iterator<Edge> vertexAdjEdgesIterator =
GraphUtilities.getVertexAdjEdges(g, a).getMembers().iterator();
while (vertexAdjEdgesIterator.hasNext()) {
Edge e = vertexAdjEdgesIterator.next();
if (((Double) c.getEdgeProperty(e)).doubleValue() > C_max) {
eMax = e;
C_max = ((Double) c.getEdgeProperty(e)).doubleValue();
}
}
pot.setVertexProperty(a, new Double(C_max));
Vertex b;
if (eMax != null
&& ((Boolean)
free.getVertexProperty((b = GraphUtilities.getEdgeTargetVertex(g, eMax))))
.booleanValue()) {
eMax.turnOverEdgeDirection();
free.setVertexProperty(a, new Boolean(false));
free.setVertexProperty(b, new Boolean(false));
}
}
break;
default:
// REFINED_HEURISTIC
mwbmHeuristic(g, c, pot, free);
break;
}
Iterator<Vertex> leftVertexesIterator = g.getLeftVertexSetIterator();
while (leftVertexesIterator.hasNext()) {
Vertex a = leftVertexesIterator.next();
if (((Boolean) free.getVertexProperty(a)).booleanValue())
augment(g, a, c, pot, free, pred, dist, PQ);
}
Iterator<Vertex> rightVertexesIterator = g.getRightVertexSetIterator();
while (rightVertexesIterator.hasNext()) {
Vertex b = rightVertexesIterator.next();
Iterator<Edge> outEdgesIterator =
GraphUtilities.getVertexOutEdges(g, b).getMembers().iterator();
while (outEdgesIterator.hasNext()) {
result.addMember(outEdgesIterator.next());
}
}
result.turnOverEdges(false);
return result;
}
/**
* The maximum weight bipartite matching heuristis
*
* @param g {@link BipartiteGraph}
* @param c an {@link EdgeArray}
* @param pot a {@link VertexArray}
* @param free free {@link VertexArray}
*/
private void mwbmHeuristic(BipartiteGraph g, EdgeArray c, VertexArray pot, VertexArray free) {
Vertex a, b;
Edge e, e2, eb;
VertexArray secEdge = new VertexArray(g, null);
Iterator<Vertex> leftVertexSetIterator = g.getLeftVertexSetIterator();
while (leftVertexSetIterator.hasNext()) {
a = (Vertex) leftVertexSetIterator.next();
double max2 = 0, max = 0;
eb = null;
e2 = null;
// compute edges with largest and second largest slack
Iterator<Edge> aAdjEdgesIterator =
GraphUtilities.getVertexAdjEdges(g, a).getMembers().iterator();
while (aAdjEdgesIterator.hasNext()) {
e = (Edge) aAdjEdgesIterator.next();
double we =
((Double) c.getEdgeProperty(e)).doubleValue()
- ((Double) pot.getVertexProperty(GraphUtilities.getEdgeTargetVertex(g, e)))
.doubleValue();
if (we >= max2) {
if (we >= max) {
max2 = max;
e2 = eb;
max = we;
eb = e;
} else {
max2 = we;
e2 = e;
}
}
}
if (eb != null) {
b = GraphUtilities.getEdgeTargetVertex(g, eb);
if (((Boolean) free.getVertexProperty(b)).booleanValue()) {
// match eb and change pot[] to make slack of e2 zero
secEdge.setVertexProperty(a, e2);
pot.setVertexProperty(a, new Double(max2));
pot.setVertexProperty(b, new Double(max - max2));
eb.turnOverEdgeDirection();
free.setVertexProperty(a, new Boolean(false));
free.setVertexProperty(b, new Boolean(false));
} else {
// try to augment matching along
// path of length 3 given by sec_edge[]
pot.setVertexProperty(a, new Double(max));
e2 = GraphUtilities.getVertexFirstAdjEdge(g, b);
e = (Edge) secEdge.getVertexProperty(GraphUtilities.getEdgeTargetVertex(g, e2));
if (e != null
&& GraphUtilities.getVertexOutDeg(g, GraphUtilities.getEdgeTargetVertex(g, e)) == 0) {
free.setVertexProperty(a, new Boolean(false));
free.setVertexProperty(GraphUtilities.getEdgeTargetVertex(g, e), new Boolean(false));
e.turnOverEdgeDirection();
e2.turnOverEdgeDirection();
eb.turnOverEdgeDirection();
}
}
} else {
pot.setVertexProperty(a, new Double(0));
}
}
}
/**
* Augment of the graph
*
* @param g {@link BipartiteGraph}
* @param a {@link Vertex}
* @param c an {@link EdgeArray}
* @param pot a {@link VertexArray}
* @param free a {@link VertexArray}
* @param pred a {@link VertexArray}
* @param dist a {@link VertexArray}
* @param PQ a vertex priority queue {@link VertexPQ}
*/
private void augment(
BipartiteGraph g,
Vertex a,
final EdgeArray c,
VertexArray pot,
VertexArray free,
VertexArray pred,
VertexArray dist,
VertexPQ PQ) {
// augument:initialization
dist.setVertexProperty(a, new Double(0));
Vertex bestVertexInA = a;
double minA = ((Double) pot.getVertexProperty(a)).doubleValue();
double Delta;
Stack<Vertex> RA = new Stack<Vertex>(), RB = new Stack<Vertex>();
RA.push(a);
Vertex a1 = a;
Edge e;
// relax all edges out of a1
Iterator<Edge> a1AdjEdgesIterator =
GraphUtilities.getVertexAdjEdges(g, a1).getMembers().iterator();
while (a1AdjEdgesIterator.hasNext()) {
e = a1AdjEdgesIterator.next();
Vertex b = GraphUtilities.getEdgeTargetVertex(g, e);
double db =
((Double) dist.getVertexProperty(a1)).doubleValue()
+ (((Double) pot.getVertexProperty(a1)).doubleValue()
+ ((Double) pot.getVertexProperty(b)).doubleValue()
- ((Double) c.getEdgeProperty(e)).doubleValue());
if (pred.getVertexProperty(b) == null) {
dist.setVertexProperty(b, new Double(db));
pred.setVertexProperty(b, e);
RB.push(b);
PQ.insert(b, new Double(db));
} else if (db < ((Double) dist.getVertexProperty(b)).doubleValue()) {
dist.setVertexProperty(b, new Double(db));
pred.setVertexProperty(b, e);
PQ.decreaseP(b, new Double(db));
}
}
while (true) {
// select from PQ the node b with minimal distance db
Vertex b;
double db = 0;
if (PQ.isEmpty()) b = null;
else {
b = (Vertex) PQ.deleteMin();
db = ((Double) dist.getVertexProperty(b)).doubleValue();
}
// distinguish three cases
if (b == null || db >= minA) {
Delta = minA;
// augmentation by path to best node in A
augmentPathTo(g, bestVertexInA, pred);
free.setVertexProperty(a, new Boolean(false));
free.setVertexProperty(bestVertexInA, new Boolean(true));
break;
} else if (((Boolean) free.getVertexProperty(b)).booleanValue()) {
Delta = db;
// augmentation by path to b
augmentPathTo(g, b, pred);
free.setVertexProperty(a, new Boolean(false));
free.setVertexProperty(b, new Boolean(false));
break;
} else {
// continue shortest-path computation
e = GraphUtilities.getVertexFirstAdjEdge(g, b);
Vertex a11 = GraphUtilities.getEdgeTargetVertex(g, e);
pred.setVertexProperty(a11, e);
RA.push(a11);
dist.setVertexProperty(a11, new Double(db));
if (db + ((Double) pot.getVertexProperty(a11)).doubleValue() < minA) {
bestVertexInA = a11;
minA = db + ((Double) pot.getVertexProperty(a11)).doubleValue();
}
// relax all edges out of a11
Iterator<Edge> a11AdjEdgesIterator =
GraphUtilities.getVertexAdjEdges(g, a11).getMembers().iterator();
while (a11AdjEdgesIterator.hasNext()) {
e = (Edge) a11AdjEdgesIterator.next();
Vertex b1 = GraphUtilities.getEdgeTargetVertex(g, e);
double db1 =
((Double) dist.getVertexProperty(a11)).doubleValue()
+ (((Double) pot.getVertexProperty(a11)).doubleValue()
+ ((Double) pot.getVertexProperty(b1)).doubleValue()
- ((Double) c.getEdgeProperty(e)).doubleValue());
if (pred.getVertexProperty(b1) == null) {
dist.setVertexProperty(b1, new Double(db1));
pred.setVertexProperty(b1, e);
RB.push(b1);
PQ.insert(b1, new Double(db1)); // PQ.insert(b1,db1)
} else if (db1 < ((Double) dist.getVertexProperty(b1)).doubleValue()) {
dist.setVertexProperty(b1, new Double(db1));
pred.setVertexProperty(b1, e);
PQ.decreaseP(b1, new Double(db1));
}
}
}
}
// augment: potential update and re-initialization
while (!RA.isEmpty()) {
Vertex a12 = (Vertex) RA.pop();
pred.setVertexProperty(a12, null);
double potChange = Delta - ((Double) dist.getVertexProperty(a12)).doubleValue();
if (potChange <= 0) continue;
pot.setVertexProperty(
a12, new Double(((Double) pot.getVertexProperty(a12)).doubleValue() - potChange));
}
while (!RB.isEmpty()) {
Vertex b12 = (Vertex) RB.pop();
pred.setVertexProperty(b12, null);
if (PQ.member(b12)) PQ.delete(b12);
double potChange = Delta - ((Double) dist.getVertexProperty(b12)).doubleValue();
if (potChange <= 0) continue;
pot.setVertexProperty(
b12, new Double(((Double) pot.getVertexProperty(b12)).doubleValue() + potChange));
}
}