Package org.apache.commons.math3.util

Class KthSelector

java.lang.Object

org.apache.commons.math3.util.KthSelector

All Implemented Interfaces:

Serializable

public class KthSelector
extends Object
implements Serializable

A Simple K^th selector implementation to pick up the K^th ordered element from a work array containing the input numbers.

Since:

3.4

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
KthSelector()	Constructor with default median of 3 pivoting strategy
KthSelector(PivotingStrategyInterface pivotingStrategy)	Constructor with specified pivoting strategy

Method Summary

Modifier and Type	Method	Description
PivotingStrategyInterface	getPivotingStrategy()	Get the pivotin strategy.
double	select(double[] work, int[] pivotsHeap, int k)	Select Kth value in the array.

Methods inherited from class java.lang.Object

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

Constructor Details

KthSelector

public KthSelector()

Constructor with default median of 3 pivoting strategy

KthSelector

public KthSelector(PivotingStrategyInterface pivotingStrategy)
            throws NullArgumentException

Constructor with specified pivoting strategy

Parameters:

pivotingStrategy - pivoting strategy to use

Throws:

NullArgumentException - when pivotingStrategy is null

See Also:

• MedianOf3PivotingStrategy
• RandomPivotingStrategy
• CentralPivotingStrategy

Method Details

getPivotingStrategy

public PivotingStrategyInterface getPivotingStrategy()

Get the pivotin strategy.

Returns:

pivoting strategy

select

public double select(double[] work,
 int[] pivotsHeap,
 int k)

Select K^th value in the array.

Parameters:

work - work array to use to find out the K^th value

pivotsHeap - cached pivots heap that can be used for efficient estimation

k - the index whose value in the array is of interest

Returns:

K^th value