@Override
public Solution pack(double upperBound) {
Set<Cycle> matching = new HashSet<Cycle>();
double objVal = 0.0;
Set<Vertex> matchedVerts = new HashSet<Vertex>();
long start = System.nanoTime();
// First, use every altruist by packing chains
if (maxChainSize > 1) {
for (Vertex alt : pool.getAltruists()) {
// Can't sample any chains from isolated altruists
if (pool.outgoingEdgesOf(alt).isEmpty()) {
continue;
}
Cycle chain = sampleAChain(alt, matchedVerts, maxChainSize, usingFailureProbabilities);
// Couldn't find a legal path from this altruist
if (null == chain) {
continue;
}
// We check legality of the chain during generation, so add all verts and chain to matching
Set<Vertex> cVerts = Cycle.getConstituentVertices(chain, pool);
matchedVerts.addAll(cVerts);
objVal += chain.getWeight();
matching.add(chain);
// If we hit the upper bound, break out
if (objVal >= upperBound) {
break;
}
}
}
// Second, pack remaining vertices in cycles (using a VertexShufflePacker)
VertexShufflePacker cyclePacker =
new VertexShufflePacker(
this.pool, this.cycles, this.membership, this.shuffleType, matchedVerts);
Solution cyclesOnly = cyclePacker.pack(upperBound - objVal);
// Add these packed cycles to our full matching
matching.addAll(cyclesOnly.getMatching());
objVal += cyclesOnly.getObjectiveValue();
long end = System.nanoTime();
long totalTime = end - start;
// Construct formal matching, return
Solution sol = new Solution();
sol.setMatching(matching);
sol.setObjectiveValue(objVal);
sol.setSolveTime(totalTime);
return sol;
}
public static void removeKidneyToLiverEdges(
Pool pool, Random r, double probKidneyToLiver, double pctKidney) {
IOUtil.dPrintln("Removing edges from some kidney donors to liver pairs.");
// First, label the vertices as either kidney- or liver-needing (all altruists are assumed
// kidney)
Set<Vertex> kidneyPairedDonors = new HashSet<Vertex>();
Set<Vertex> liverPairedDonors = new HashSet<Vertex>();
for (VertexPair vp : pool.getPairs()) {
if (r.nextDouble() < pctKidney) {
kidneyPairedDonors.add(vp);
} else {
liverPairedDonors.add(vp);
}
}
for (VertexAltruist alt : pool.getAltruists()) {
kidneyPairedDonors.add(alt);
}
// Next, for each kidney-paired donor, determine if that donor is willing
// to give a liver. If not, remove all outgoing edges to liver-paired donors
Set<Edge> edgesToRemove = new HashSet<Edge>();
for (Vertex kidneyV : kidneyPairedDonors) {
boolean willingToGive = (r.nextDouble() < probKidneyToLiver);
willingToGive &=
!(kidneyV.isAltruist()); // disallow any kidney altruists from given to liver pairs
if (willingToGive) {
continue;
}
for (Edge e : pool.outgoingEdgesOf(kidneyV)) {
if (liverPairedDonors.contains(pool.getEdgeTarget(e))) {
edgesToRemove.add(e);
}
}
}
int removedEdgeCt = 0;
for (Edge e : edgesToRemove) {
pool.removeEdge(e);
removedEdgeCt++;
}
IOUtil.dPrintln(
"Removed "
+ removedEdgeCt
+ " edges from kidney donors to liver pairs ("
+ pool.edgeSet().size()
+ " remain).");
}