/**
* Wraps a {@link BinaryMatrix} instance with a {@link PairSet} instance.
*
* <p><b>NOTE:</b> the maximum item and transaction IDs are those existing in the binary matrix
* when the wrapping take place
*
* @param b a {@link BinaryMatrix} instance to wrap
* @return a new {@link PairSet} instance, indexed by the given matrix
*/
public static PairSet<Integer, Integer> createFromBinaryMatrix(BinaryMatrix b) {
// TODO this is a little bit costly since PairSet will allocate an array
// and a HashMap of Integers to map elements of BinaryMatrix...
// Think about a IntegerPairSet class or to an "fake" IntegerIndexedSet
// just for this purpose.
IntegerSet t = new IntegerSet(b.emptyRow());
t.intSet().add(b.maxRow() + 1);
t.intSet().complement();
IntegerSet i = new IntegerSet(b.emptyRow());
i.intSet().add(b.maxCol() + 1);
i.intSet().complement();
return new PairSet<Integer, Integer>(b, t, i);
}
/**
* Initializes the set by specifying all possible transactions and items.
*
* @param matrix {@link BinaryMatrix} instance used to internally represent the matrix
* @param transactions collection of <i>all</i> possible transactions. The specified order will be
* preserved within when iterating over the {@link PairSet} instance.
* @param items collection of <i>all</i> possible items. The specified order will be preserved
* within each transaction {@link PairSet}.
*/
public PairSet(BinaryMatrix matrix, Collection<T> transactions, Collection<I> items) {
if (transactions == null || items == null) throw new NullPointerException();
this.matrix = matrix;
IntSet tmp = matrix.emptyRow();
if (transactions instanceof IndexedSet<?>) allTransactions = (IndexedSet<T>) transactions;
else
allTransactions = new IndexedSet<T>(tmp.empty(), transactions).universe(); // .unmodifiable();
if (items instanceof IndexedSet<?>) allItems = (IndexedSet<I>) items;
else allItems = new IndexedSet<I>(tmp.empty(), items).universe(); // .unmodifiable();
}
