weka.associations

Class RuleItem

java.lang.Object

weka.associations.RuleItem

All Implemented Interfaces:

Serializable, Comparable, RevisionHandler

public class RuleItem
extends Object
implements Comparable, Serializable, RevisionHandler

Class for storing an (class) association rule. The premise and the consequence are stored each as separate item sets. For every rule their expected predictive accuracy and the time of generation is stored. These two measures allow to introduce a sort order for rules.

Version:

$Revision: 1.5 $

Author:

Stefan Mutter

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
RuleItem() Constructor for an empty RuleItem
RuleItem(ItemSet premise, ItemSet consequence, int genTime, int ruleSupport, double[] m_midPoints, Hashtable m_priors) Constructor
RuleItem(RuleItem toCopy) Constructor that generates a RuleItem out of a given one

Method Summary

Modifier and Type	Method and Description
double	accuracy() Gets the expected predictive accuracy of a rule
int	compareTo(Object o) compares two RuleItems and allows an ordering concerning expected predictive accuracy and time of generation Note: this class has a natural ordering that is inconsistent with equals
ItemSet	consequence() Gets the consequence of a rule
boolean	equals(Object o) returns whether two RuleItems are equal
RuleItem	generateRuleItem(ItemSet premise, ItemSet consequence, Instances instances, int genTime, int minRuleCount, double[] m_midPoints, Hashtable m_priors) Constructs a new RuleItem if the support of the given rule is above the support threshold.
String	getRevision() Returns the revision string.
ItemSet	premise() Gets the premise of a rule

Methods inherited from class java.lang.Object

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

Constructor Detail

RuleItem

public RuleItem()

Constructor for an empty RuleItem

RuleItem

public RuleItem(RuleItem toCopy)

Constructor that generates a RuleItem out of a given one

Parameters:

toCopy - RuleItem to copy

RuleItem

public RuleItem(ItemSet premise,
                ItemSet consequence,
                int genTime,
                int ruleSupport,
                double[] m_midPoints,
                Hashtable m_priors)

Constructor

Parameters:

premise - the premise of the future RuleItem

consequence - the consequence of the future RuleItem

genTime - the time of generation of the future RuleItem

ruleSupport - support of the rule

m_midPoints - the mid poitns of the intervals

m_priors - Hashtable containing the estimated prior probablilities

Method Detail

generateRuleItem

public RuleItem generateRuleItem(ItemSet premise,
                                 ItemSet consequence,
                                 Instances instances,
                                 int genTime,
                                 int minRuleCount,
                                 double[] m_midPoints,
                                 Hashtable m_priors)

Constructs a new RuleItem if the support of the given rule is above the support threshold.

Parameters:

premise - the premise

consequence - the consequence

instances - the instances

genTime - the time of generation of the current premise and consequence

minRuleCount - the support threshold

m_midPoints - the mid points of the intervals

m_priors - the estimated priori probabilities (in a hashtable)

Returns:

a RuleItem if its support is above the threshold, null otherwise

compareTo

public int compareTo(Object o)

compares two RuleItems and allows an ordering concerning expected predictive accuracy and time of generation Note: this class has a natural ordering that is inconsistent with equals

Specified by:

compareTo in interface Comparable

Parameters:

o - RuleItem to compare

Returns:

integer indicating the sort oder of the two RuleItems

equals

public boolean equals(Object o)

returns whether two RuleItems are equal

Overrides:

equals in class Object

Parameters:

o - RuleItem to compare

Returns:

true if the rules are equal, false otherwise

accuracy

public double accuracy()

Gets the expected predictive accuracy of a rule

Returns:

the expected predictive accuracy of a rule stored as a RuleItem

premise

public ItemSet premise()

Gets the premise of a rule

Returns:

the premise of a rule stored as a RuleItem

consequence

public ItemSet consequence()

Gets the consequence of a rule

Returns:

the consequence of a rule stored as a RuleItem

getRevision

public String getRevision()

Returns the revision string.

Specified by:

getRevision in interface RevisionHandler

Returns:

the revision