private static ItemSet icc() {
ItemSet bestItemSet = null;
int itemNumber = data.getTuples()[0].getItemSet().getLength();
double bestItemScore = 0.0;
Set<ItemSet> Q1 = new HashSet<ItemSet>();
Set<ItemSet> B1 = new HashSet<ItemSet>(Q1);
System.out.println("ICC init, with " + itemNumber + " items");
for (int j = 0; j < itemNumber; j++) {
ItemSet itemSet = getData().getBluePrint().getOneItemSet(j, itemNumber);
double newScore = iccUpdate(itemSet, Q1, bestItemScore);
if (newScore != bestItemScore) {
bestItemSet = itemSet;
bestItemScore = newScore;
}
}
System.out.println("ICC init finished");
Set<ItemSet> QVorige = new HashSet<ItemSet>();
QVorige.addAll(Q1);
Set<ItemSet> QVolgende = QVorige;
while (!QVolgende.isEmpty()) {
QVolgende = new HashSet<ItemSet>();
for (ItemSet B : Q1) {
for (ItemSet Q : QVorige) {
int lastSetBit = 0;
for (int i = Q.getBitSet().nextSetBit(0); i >= 0; i = Q.getBitSet().nextSetBit(i + 1))
lastSetBit = i;
if (lastSetBit < B.getBitSet().nextSetBit(0) && Q.ub() >= bestItemScore) {
if (B.ub() < bestItemScore) B1.remove(B);
else {
ItemSet itemSet = Q.union(B);
double newScore = iccUpdate(itemSet, QVolgende, bestItemScore);
if (newScore != bestItemScore) {
bestItemSet = itemSet;
bestItemScore = newScore;
}
}
}
}
}
QVorige = QVolgende;
}
return bestItemSet;
}
private static double iccUpdate(ItemSet itemSet, Set<ItemSet> itemSets, double bestItemScore) {
if (itemSet.ub() >= bestItemScore) {
itemSets.add(itemSet);
DataSet covered = data.matching(itemSet);
double itemSetValue = var(covered.getTuples().length, covered.y());
if (itemSetValue > bestItemScore) {
return itemSetValue;
}
}
return bestItemScore;
}