org.apache.commons.math3.stat.ranking

## Class NaturalRanking

- java.lang.Object
- - org.apache.commons.math3.stat.ranking.NaturalRanking

- All Implemented Interfaces:
    RankingAlgorithm

      public class NaturalRanking
      extends Object
      implements RankingAlgorithm

  Ranking based on the natural ordering on doubles.

  NaNs are treated according to the configured `NaNStrategy` and ties are handled using the selected `TiesStrategy`. Configuration settings are supplied in optional constructor arguments. Defaults are `NaNStrategy.FAILED` and `TiesStrategy.AVERAGE`, respectively. When using `TiesStrategy.RANDOM`, a `RandomGenerator` may be supplied as a constructor argument.

  Examples:

  Input data: (20, 17, 30, 42.3, 17, 50, Double.NaN, Double.NEGATIVE_INFINITY, 17)
  NaNStrategy | TiesStrategy | `rank(data)`
  --- | --- | ---
  default (NaNs maximal) | default (ties averaged) | (5, 3, 6, 7, 3, 8, 9, 1, 3)
  default (NaNs maximal) | MINIMUM | (5, 2, 6, 7, 2, 8, 9, 1, 2)
  MINIMAL | default (ties averaged) | (6, 4, 7, 8, 4, 9, 1.5, 1.5, 4)
  REMOVED | SEQUENTIAL | (5, 2, 6, 7, 3, 8, 1, 4)
  MINIMAL | MAXIMUM | (6, 5, 7, 8, 5, 9, 2, 2, 5)

  Since:
    2.0

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static NaNStrategy` | `DEFAULT_NAN_STRATEGY` default NaN strategy
    `static TiesStrategy` | `DEFAULT_TIES_STRATEGY` default ties strategy

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `NaturalRanking()` Create a NaturalRanking with default strategies for handling ties and NaNs.
    `NaturalRanking(NaNStrategy nanStrategy)` Create a NaturalRanking with the given NaNStrategy.
    `NaturalRanking(NaNStrategy nanStrategy, RandomGenerator randomGenerator)` Create a NaturalRanking with the given NaNStrategy, TiesStrategy.RANDOM and the given source of random data.
    `NaturalRanking(NaNStrategy nanStrategy, TiesStrategy tiesStrategy)` Create a NaturalRanking with the given NaNStrategy and TiesStrategy.
    `NaturalRanking(RandomGenerator randomGenerator)` Create a NaturalRanking with TiesStrategy.RANDOM and the given RandomGenerator as the source of random data.
    `NaturalRanking(TiesStrategy tiesStrategy)` Create a NaturalRanking with the given TiesStrategy.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `NaNStrategy` | `getNanStrategy()` Return the NaNStrategy
    `TiesStrategy` | `getTiesStrategy()` Return the TiesStrategy
    `double[]` | `rank(double[] data)` Rank `data` using the natural ordering on Doubles, with NaN values handled according to `nanStrategy` and ties resolved using `tiesStrategy.`

    - ### Methods inherited from class java.lang.Object

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

- - ### Field Detail

    - #### DEFAULT_NAN_STRATEGY

          public static final NaNStrategy DEFAULT_NAN_STRATEGY

      default NaN strategy

    - #### DEFAULT_TIES_STRATEGY

          public static final TiesStrategy DEFAULT_TIES_STRATEGY

      default ties strategy

  - ### Constructor Detail

    - #### NaturalRanking

          public NaturalRanking()

      Create a NaturalRanking with default strategies for handling ties and NaNs.

    - #### NaturalRanking

          public NaturalRanking(TiesStrategy tiesStrategy)

      Create a NaturalRanking with the given TiesStrategy.
      Parameters:
        `tiesStrategy` - the TiesStrategy to use

    - #### NaturalRanking

          public NaturalRanking(NaNStrategy nanStrategy)

      Create a NaturalRanking with the given NaNStrategy.
      Parameters:
        `nanStrategy` - the NaNStrategy to use

    - #### NaturalRanking

          public NaturalRanking(NaNStrategy nanStrategy,
                        TiesStrategy tiesStrategy)

      Create a NaturalRanking with the given NaNStrategy and TiesStrategy.
      Parameters:
        `nanStrategy` - NaNStrategy to use
        `tiesStrategy` - TiesStrategy to use

    - #### NaturalRanking

          public NaturalRanking(RandomGenerator randomGenerator)

      Create a NaturalRanking with TiesStrategy.RANDOM and the given RandomGenerator as the source of random data.
      Parameters:
        `randomGenerator` - source of random data

    - #### NaturalRanking

          public NaturalRanking(NaNStrategy nanStrategy,
                        RandomGenerator randomGenerator)

      Create a NaturalRanking with the given NaNStrategy, TiesStrategy.RANDOM and the given source of random data.
      Parameters:
        `nanStrategy` - NaNStrategy to use
        `randomGenerator` - source of random data

  - ### Method Detail

    - #### getNanStrategy

          public NaNStrategy getNanStrategy()

      Return the NaNStrategy
      Returns:
        returns the NaNStrategy

    - #### getTiesStrategy

          public TiesStrategy getTiesStrategy()

      Return the TiesStrategy
      Returns:
        the TiesStrategy

    - #### rank

          public double[] rank(double[] data)

      Rank `data` using the natural ordering on Doubles, with NaN values handled according to `nanStrategy` and ties resolved using `tiesStrategy.`
      Specified by:
        `rank` in interface `RankingAlgorithm`
      Parameters:
        `data` - array to be ranked
      Returns:
        array of ranks
      Throws:
        `NotANumberException` - if the selected `NaNStrategy` is `FAILED` and a `Double.NaN` is encountered in the input data

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