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

Constructors
Constructor	Description
`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

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`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