/**
* Perform the intersection of two diffsets for itemsets containing more than one item.
*
* @param tidsetI the first diffset
* @param tidsetJ the second diffset
* @return the resulting diffset and its support
*/
BitSetSupport performAND(BitSetSupport tidsetI, BitSetSupport tidsetJ) {
// Create the new diffset
BitSetSupport bitsetSupportIJ = new BitSetSupport();
// Calculate the diffset
bitsetSupportIJ.bitset = (BitSet) tidsetJ.bitset.clone();
bitsetSupportIJ.bitset.andNot(tidsetI.bitset);
// Calculate the support
bitsetSupportIJ.support = tidsetI.support - bitsetSupportIJ.bitset.cardinality();
// return the new diffset
return bitsetSupportIJ;
}
/**
* Perform the intersection of two diffsets representing single items.
*
* @param tidsetI the first diffset
* @param tidsetJ the second diffset
* @param supportIJ the support of the intersection (already known) so it does not need to be
* calculated again
* @return the resulting diffset and its support
*/
BitSetSupport performANDFirstTime(BitSetSupport tidsetI, BitSetSupport tidsetJ, int supportIJ) {
// Create the new diffset and perform the logical AND to intersect the diffsets
BitSetSupport bitsetSupportIJ = new BitSetSupport();
// Calculate the diffset
bitsetSupportIJ.bitset = (BitSet) tidsetJ.bitset.clone();
bitsetSupportIJ.bitset.andNot(tidsetI.bitset);
// Calculate the support
bitsetSupportIJ.support = tidsetI.support - bitsetSupportIJ.bitset.cardinality();
// return the new tidset
return bitsetSupportIJ;
}
