ca.pfv.spmf.algorithms.frequentpatterns.apriori_HT

Class ItemsetHashTree

java.lang.Object

ca.pfv.spmf.algorithms.frequentpatterns.apriori_HT.ItemsetHashTree

public class ItemsetHashTree
extends java.lang.Object

This class represents an itemset hash tree as used by the AprioriHT algorithm (a version of Apriori implemented with a hash tree).

In the original Apriori paper it is suggested to not subdivide a node until there is enough itemsets in that node. In this implementations, all nodes are always subdivided.

See Also:

AlgoAprioriHT

Constructor Summary

Constructors

Constructor and Description
ItemsetHashTree(int itemsetSize, int branch_count) Constructor

Method Summary

Modifier and Type	Method and Description
void	insertCandidateItemset(Itemset itemset) Inserts an itemset in the hash-tree
boolean	isInTheTree(int[] itemset, int posRemoved) This method checks if an itemset exists in the tree.
void	updateSupportCount(int[] transaction) This method increase the support count of all itemsets contained in the hash-tree that are contained in a transaction.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ItemsetHashTree

public ItemsetHashTree(int itemsetSize,
                       int branch_count)

Constructor

Parameters:

itemsetSize - the size of the itemsets that will be inserted in the tree

Method Detail

insertCandidateItemset

public void insertCandidateItemset(Itemset itemset)

Inserts an itemset in the hash-tree

Parameters:

itemset - the itemset to be inserted

updateSupportCount

public void updateSupportCount(int[] transaction)

This method increase the support count of all itemsets contained in the hash-tree that are contained in a transaction.

Parameters:

transaction - the transaction.

isInTheTree

public boolean isInTheTree(int[] itemset,
                           int posRemoved)

This method checks if an itemset exists in the tree.

Parameters:

itemset - the itemset

posRemoved - the position of an item that should be ignored in this itemset

Returns:

true if the itemset appears in the tree