org.apache.commons.math3.util

Class RandomPivotingStrategy

java.lang.Object

org.apache.commons.math3.util.RandomPivotingStrategy

All Implemented Interfaces:

java.io.Serializable, PivotingStrategyInterface

public class RandomPivotingStrategy
extends java.lang.Object
implements PivotingStrategyInterface, java.io.Serializable

A strategy of selecting random index between begin and end indices.

Since:

3.4

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private RandomGenerator	random Random generator to use for selecting pivot.
private static long	serialVersionUID Serializable UID.

Constructor Summary

Constructors

Constructor and Description
RandomPivotingStrategy(RandomGenerator random) Simple constructor.

Method Summary

Methods

Modifier and Type	Method and Description
int	pivotIndex(double[] work, int begin, int end) Find pivot index of the array so that partition and Kth element selection can be made

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

serialVersionUID

private static final long serialVersionUID

Serializable UID.

See Also:

Constant Field Values

random

private final RandomGenerator random

Random generator to use for selecting pivot.

Constructor Detail

RandomPivotingStrategy

public RandomPivotingStrategy(RandomGenerator random)

Simple constructor.

Parameters:

random - random generator to use for selecting pivot

Method Detail

pivotIndex

public int pivotIndex(double[] work,
             int begin,
             int end)
               throws MathIllegalArgumentException

Find pivot index of the array so that partition and K^th element selection can be made A uniform random pivot selection between begin and end indices

Specified by:

pivotIndex in interface PivotingStrategyInterface

Parameters:

work - data array

begin - index of the first element of the slice

end - index after the last element of the slice

Returns:

The index corresponding to a random uniformly selected value between first and the last indices of the array slice

Throws:

MathIllegalArgumentException - when indices exceeds range