ca.pfv.spmf.algorithms.frequentpatterns.apriori_HT

Class AlgoAprioriHT

java.lang.Object

ca.pfv.spmf.algorithms.frequentpatterns.apriori_HT.AlgoAprioriHT

public class AlgoAprioriHT
extends java.lang.Object

This is an implementation of the Apriori algorithm that use an Hash-tree to store candidates, to calculate their support and to generate candidates efficiently. The other version (AlgoApriori) do not use a hash tree.

The Apriori algorithm is described in :

Agrawal R, Srikant R. "Fast Algorithms for Mining Association Rules", VLDB. Sep 12-15 1994, Chile, 487-99,

The Apriori algorithm finds all the frequents itemsets and their support in a transaction database.

Note that the performance of the Hash-Tree version of Apriori depends on the BRANCH COUNT value in the class ItemsetHashTree. In my test, I have used a value of 30 because it seems to provide the best results. But other values could also be used (see Agrawal & Srikant for details). To change the branch_count variable, see the ItemsetHashTree class (default is 30).

See Also:

Itemset, AbstractOrderedItemsetsAdapter, ItemsetHashTree

Constructor Summary

Constructors

Constructor and Description
AlgoAprioriHT() Default constructor

Method Summary

Modifier and Type	Method and Description
void	printStats() Method to print statistics about the execution of the algorithm.
void	runAlgorithm(double minsup, java.lang.String input, java.lang.String output, int hash_tree_branch_count) Run the Apriori-HT algorithm

Methods inherited from class java.lang.Object

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

Constructor Detail

AlgoAprioriHT

public AlgoAprioriHT()

Default constructor

Method Detail

runAlgorithm

public void runAlgorithm(double minsup,
                         java.lang.String input,
                         java.lang.String output,
                         int hash_tree_branch_count)
                  throws java.io.IOException

Run the Apriori-HT algorithm

Parameters:

minsup - the minimum support threshold

input - path to the input file

output - path to save the result to an output file

hash_tree_branch_count - the number of child nodes for each node in the hash tree

Throws:

java.io.IOException - if an error while reading/writing files

printStats

public void printStats()

Method to print statistics about the execution of the algorithm.