Impurity

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## weka.classifiers.trees.m5
Class Impurity

    java.lang.Object
      weka.classifiers.trees.m5.Impurity

All Implemented Interfaces:
  RevisionHandler

    public final class Impurity

extends java.lang.Object
implements RevisionHandler

Class for handling the impurity values when spliting the instances

Version:
  $Revision: 1.8 $
Author:
  Yong Wang (yongwang@cs.waikato.ac.nz)

Constructor Summary
`Impurity(int partition, int attribute, Instances inst, int k)` Constructs an Impurity object containing the impurity values of partitioning the instances using an attribute

Method Summary
`java.lang.String` | `getRevision()` Returns the revision string.
`void` | `incremental(double value, int type)` Incrementally computes the impurirty values
`java.lang.String` | `toString()` Converts an Impurity object to a string

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

Constructor Detail

### Impurity

    public Impurity(int partition,
                    int attribute,
                    Instances inst,
                    int k)

  Constructs an Impurity object containing the impurity values of partitioning the instances using an attribute

  Parameters:
    `partition` - the index of the last instance in the left subset
    `attribute` - the attribute used in partitioning
    `inst` - instances
    `k` - the order of the impurity; =1, the variance; =2, the stardard deviation; =k, the k-th order root of the variance

Method Detail

### toString

    public final java.lang.String toString()

  Converts an Impurity object to a string

  Overrides:
    `toString` in class `java.lang.Object`
  Returns:
    the converted string

### incremental

    public final void incremental(double value,
                                  int type)

  Incrementally computes the impurirty values

  Parameters:
    `value` - the incremental value
    `type` - if type=1, value will be added to the left subset; type=-1, to the right subset; type=0, initializes

### getRevision

    public java.lang.String getRevision()

  Returns the revision string.

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

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