Package org.apache.commons.math3.stat.descriptive.rank

Class PSquarePercentile

java.lang.Object
org.apache.commons.math3.stat.descriptive.AbstractUnivariateStatistic
org.apache.commons.math3.stat.descriptive.AbstractStorelessUnivariateStatistic
org.apache.commons.math3.stat.descriptive.rank.PSquarePercentile
All Implemented Interfaces:
Serializable, StorelessUnivariateStatistic, UnivariateStatistic, MathArrays.Function
public class PSquarePercentile extends AbstractStorelessUnivariateStatistic implements StorelessUnivariateStatistic, Serializable
A StorelessUnivariateStatistic estimating percentiles using the invalid input: '<'ahref=http://www.cs.wustl.edu/~jain/papers/ftp/psqr.pdf>P2 Algorithm as explained by Raj Jain and Imrich Chlamtac in P2 Algorithm for Dynamic Calculation of Quantiles and Histogram Without Storing Observations.

Note: This implementation is not synchronized and produces an approximate result. For small samples, where data can be stored and processed in memory, Percentile should be used.

See Also:

  • Field Details

    • PSQUARE_CONSTANT

      private static final int PSQUARE_CONSTANT
      The maximum array size used for psquare algorithm
      See Also:

    • DEFAULT_QUANTILE_DESIRED

      private static final double DEFAULT_QUANTILE_DESIRED
      A Default quantile needed in case if user prefers to use default no argument constructor.
      See Also:

    • serialVersionUID

      private static final long serialVersionUID
      Serial ID
      See Also:

    • DECIMAL_FORMAT

      private static final DecimalFormat DECIMAL_FORMAT
      A decimal formatter for print convenience

    • initialFive

      private final List<Double> initialFive
      Initial list of 5 numbers corresponding to 5 markers. NOTE:watch out for the add methods that are overloaded

    • quantile

      private final double quantile
      The quantile needed should be in range of 0-1. The constructor PSquarePercentile(double) ensures that passed in percentile is divided by 100.

    • lastObservation

      private transient double lastObservation
      lastObservation is the last observation value/input sample. No need to serialize

    • markers

      private PSquarePercentile.PSquareMarkers markers
      Markers is the marker collection object which comes to effect only after 5 values are inserted

    • pValue

      private double pValue
      Computed p value (i,e percentile value of data set hither to received)

    • countOfObservations

      private long countOfObservations
      Counter to count the values/observations accepted into this data set

  • Constructor Details

    • PSquarePercentile

      public PSquarePercentile(double p)
      Constructs a PSquarePercentile with the specific percentile value.
      Parameters:
      p - the percentile
      Throws:
      OutOfRangeException - if p is not greater than 0 and less than or equal to 100

    • PSquarePercentile

      PSquarePercentile()
      Default constructor that assumes a default quantile needed

  • Method Details

    • hashCode

      public int hashCode()
      Returns hash code based on getResult() and getN()
      Overrides:
      hashCode in class AbstractStorelessUnivariateStatistic
      Returns:
      hash code

    • equals

      public boolean equals(Object o)
      Returns true iff o is a PSquarePercentile returning the same values as this for getResult() and getN() and also having equal markers
      Overrides:
      equals in class AbstractStorelessUnivariateStatistic
      Parameters:
      o - object to compare
      Returns:
      true if o is a PSquarePercentile with equivalent internal state

    • increment

      public void increment(double observation)
      Updates the internal state of the statistic to reflect the addition of the new value.The internal state updated due to the new value in this context is basically of the marker positions and computation of the approximate quantile.
      Specified by:
      increment in interface StorelessUnivariateStatistic
      Specified by:
      increment in class AbstractStorelessUnivariateStatistic
      Parameters:
      observation - the observation currently being added.

    • toString

      public String toString()
      Returns a string containing the last observation, the current estimate of the quantile and all markers.
      Overrides:
      toString in class Object
      Returns:
      string representation of state data

    • getN

      public long getN()
      Returns the number of values that have been added.
      Specified by:
      getN in interface StorelessUnivariateStatistic
      Returns:
      the number of values.

    • copy

      public StorelessUnivariateStatistic copy()
      Returns a copy of the statistic with the same internal state.
      Specified by:
      copy in interface StorelessUnivariateStatistic
      Specified by:
      copy in interface UnivariateStatistic
      Specified by:
      copy in class AbstractStorelessUnivariateStatistic
      Returns:
      a copy of the statistic

    • quantile

      public double quantile()
      Returns the quantile estimated by this statistic in the range [0.0-1.0]
      Returns:
      quantile estimated by getResult()

    • clear

      public void clear()
      Clears the internal state of the Statistic. This basically clears all the markers, the initialFive list and sets countOfObservations to 0.
      Specified by:
      clear in interface StorelessUnivariateStatistic
      Specified by:
      clear in class AbstractStorelessUnivariateStatistic

    • getResult

      public double getResult()
      Returns the current value of the Statistic.
      Specified by:
      getResult in interface StorelessUnivariateStatistic
      Specified by:
      getResult in class AbstractStorelessUnivariateStatistic
      Returns:
      value of the statistic, Double.NaN if it has been cleared or just instantiated.

    • maximum

      private double maximum()
      Returns:
      maximum in the data set added to this statistic

    • minimum

      private double minimum()
      Returns:
      minimum in the data set added to this statistic

    • newMarkers

      public static PSquarePercentile.PSquareMarkers newMarkers(List<Double> initialFive, double p)
      A creation method to build Markers
      Parameters:
      initialFive - list of initial five elements
      p - the quantile desired
      Returns:
      an instance of PSquareMarkers