com.pervasive.datarush.analytics.arm

Class ItemSet

java.lang.Object

com.pervasive.datarush.analytics.arm.ItemSet

All Implemented Interfaces:

Serializable

public class ItemSet
extends Object
implements Serializable

A representation of a set of items with their support (frequency) within a data set. Items are represented by int values. It is assumed that each item has a distinct integer identifier.

The necessary methods are implemented allowing instances of this class to be used within the standard utility library (i.e. HashMap ...).

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ItemSet(int itemID) Construct an item set with a single item.
ItemSet(int[] itemIDs) Construct an item set from the given items.
ItemSet(int[] itemIDs, int length) Create an item set from the list of items specifying how many from the list to use.
ItemSet(int[] itemsLHS, int[] itemsRHS) Combine the two sets of items into one set.
ItemSet(int[] itemIDs, long support, double supportPct) Construct an item set from the given items.
ItemSet(int itemID, int[] itemIDs) Combine the given singular item and a list of items into a single item set.

Method Summary

Modifier and Type	Method and Description
void	calculateSupportPct(long transactionTotal) Given the number of transactions in a DB compute the support percent for this item set.
boolean	equals(Object o)
int[]	getItemIDs() Get the item identifiers contained in this item list.
long	getSupport() Get the current support value.
double	getSupportPct() Get the support percentage value.
int	hashCode()
void	incrementSupport() Increment the support value.
static Comparator<ItemSet>	newSetSizeComparator() Create a new Comparator that compares item sets and allows sorting by item set size and support.
boolean	represents(int[] items) Returns whether the given list of items matches the list of items within this item set.
void	setSupport(long support) Set the support value.
int	size() Return the size of this item set.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

ItemSet

public ItemSet(int itemID)

Construct an item set with a single item.

Parameters:

itemID - item identifier

ItemSet

public ItemSet(int[] itemIDs)

Construct an item set from the given items. Assume ownership of the array.

Parameters:

itemIDs - items within the item set

ItemSet

public ItemSet(int[] itemIDs,
               long support,
               double supportPct)

Construct an item set from the given items. Assume ownership of the array. Use the given support values for initial values.

Parameters:

itemIDs - items within the item set

support - the initial support value

supportPct - the initial support percentage value

ItemSet

public ItemSet(int itemID,
               int[] itemIDs)

Combine the given singular item and a list of items into a single item set.

Parameters:

itemID - the singular item

itemIDs - a list of items

ItemSet

public ItemSet(int[] itemsLHS,
               int[] itemsRHS)

Combine the two sets of items into one set.

Parameters:

itemsLHS - a list of item identifiers

itemsRHS - a list of item identifiers

ItemSet

public ItemSet(int[] itemIDs,
               int length)

Create an item set from the list of items specifying how many from the list to use.

Parameters:

itemIDs - the item identifiers

length - the number of items to include

Method Detail

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

represents

public boolean represents(int[] items)

Returns whether the given list of items matches the list of items within this item set.

Parameters:

items - item identifiers

Returns:

true if all items match, false otherwise

size

public int size()

Return the size of this item set.

Returns:

the size of the item set

getItemIDs

public int[] getItemIDs()

Get the item identifiers contained in this item list.

Returns:

list of item identifiers

toString

public String toString()

Overrides:

toString in class Object

calculateSupportPct

public void calculateSupportPct(long transactionTotal)

Given the number of transactions in a DB compute the support percent for this item set.

Parameters:

transactionTotal - total number of transactions

getSupportPct

public double getSupportPct()

Get the support percentage value.

Returns:

support percentage (support / transaction count)

incrementSupport

public void incrementSupport()

Increment the support value.

getSupport

public long getSupport()

Get the current support value.

Returns:

support value

setSupport

public void setSupport(long support)

Set the support value.

Parameters:

support - support value to set

newSetSizeComparator

public static Comparator<ItemSet> newSetSizeComparator()

Create a new Comparator that compares item sets and allows sorting by item set size and support.

Returns:

a new Comparator instance