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## weka.core
Class InstanceComparator

    java.lang.Object
      weka.core.InstanceComparator

All Implemented Interfaces:
  java.io.Serializable, java.util.Comparator, RevisionHandler

    public class InstanceComparator

extends java.lang.Object
implements java.util.Comparator, java.io.Serializable, RevisionHandler

A comparator for the Instance class. it can be used with or without the class label. Missing values are sorted at the beginning. Can be used as comparator in the sorting and binary search algorithms of `Arrays` and `Collections`. Relational values are compared instance by instance with a nested InstanceComparator.

Version:
  $Revision: 7988 $
Author:
  FracPete (fracpete at cs dot waikato dot ac dot nz)
See Also:
  `Instance`, `Arrays`, `Collections`, Serialized Form

Constructor Summary
`InstanceComparator()` initializes the comparator and includes the class in the comparison
`InstanceComparator(boolean includeClass)` initializes the comparator

Method Summary
`int` | `compare(java.lang.Object o1, java.lang.Object o2)` compares the two instances, returns -1 if o1 is smaller than o2, 0 if equal and +1 if greater.
`boolean` | `getIncludeClass()` returns TRUE if the class is included in the comparison
`java.lang.String` | `getRevision()` Returns the revision string.
`static void` | `main(java.lang.String[] args)` for testing only.
`void` | `setIncludeClass(boolean includeClass)` sets whether the class should be included (= TRUE) in the comparison

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface java.util.Comparator
`equals`

Constructor Detail

### InstanceComparator

    public InstanceComparator()

  initializes the comparator and includes the class in the comparison

### InstanceComparator

    public InstanceComparator(boolean includeClass)

  initializes the comparator

Method Detail

### setIncludeClass

    public void setIncludeClass(boolean includeClass)

  sets whether the class should be included (= TRUE) in the comparison

  Parameters:
    `includeClass` - whether to include the class in the comparison

### getIncludeClass

    public boolean getIncludeClass()

  returns TRUE if the class is included in the comparison

### compare

    public int compare(java.lang.Object o1,
                       java.lang.Object o2)

  compares the two instances, returns -1 if o1 is smaller than o2, 0 if equal and +1 if greater. The method assumes that both instance objects have the same attributes, they don't have to belong to the same dataset.

  Specified by:
    `compare` in interface `java.util.Comparator`
  Parameters:
    `o1` - the first instance to compare
    `o2` - the second instance to compare
  Returns:
    returns -1 if o1 is smaller than o2, 0 if equal and +1 if greater

### getRevision

    public java.lang.String getRevision()

  Returns the revision string.

  Specified by:
    `getRevision` in interface `RevisionHandler`
  Returns:
    the revision

### main

    public static void main(java.lang.String[] args)
                     throws java.lang.Exception

  for testing only. takes an ARFF-filename as first argument to perform some tests.

  Throws:
    `java.lang.Exception`

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