KthSelector (VirtualDataSet API)

java.lang.Object
- org.apache.commons.math4.util.KthSelector

All Implemented Interfaces:

java.io.Serializable
```
public class KthSelector
extends java.lang.Object
implements java.io.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 K^th value in the array.

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

- Constructor Detail
  - 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 Detail
  - 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