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## weka.associations
Class RuleItem

    java.lang.Object
      weka.associations.RuleItem

All Implemented Interfaces:
  java.io.Serializable, java.lang.Comparable

    public class RuleItem

extends java.lang.Object
implements java.lang.Comparable, java.io.Serializable

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: 1.1.2.1 $
Author:
  Stefan Mutter
See Also:
  Serialized Form

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

Method Summary
`double` | `accuracy()` Gets the expected predictive accuracy of a rule
`int` | `compareTo(java.lang.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(java.lang.Object o)` returns whether two RuleItems are equal
`RuleItem` | `generateRuleItem(ItemSet premise, ItemSet consequence, Instances instances, int genTime, int minRuleCount, double[] m_midPoints, java.util.Hashtable m_priors)` Constructs a new RuleItem if the support of the given rule is above the support threshold.
`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,
                    java.util.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,
                                     java.util.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(java.lang.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 `java.lang.Comparable`
  Parameters:
    `o` - RuleItem to compare
  Returns:
    integer indicating the sort oder of the two RuleItems

### equals

    public boolean equals(java.lang.Object o)

  returns whether two RuleItems are equal

  Overrides:
    `equals` in class `java.lang.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

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