Module io.jenetics.base
Package io.jenetics.stat

Class DoubleMomentStatistics

java.lang.Object
io.jenetics.stat.DoubleMomentStatistics
All Implemented Interfaces:
DoubleConsumer
public class DoubleMomentStatistics extends Object implements DoubleConsumer
A state object for collecting statistics such as count, min, max, sum, mean, variance, skewness and kurtosis. The design of this class is similar to the DoubleSummaryStatistics class.

This class is designed to work with (though does not require) streams. For example, you can compute moments-statistics on a stream of doubles with: 

final DoubleStream stream = ...;
final DoubleMomentStatistics statistics = stream.collect(
        DoubleMomentStatistics::new,
        DoubleMomentStatistics::accept,
        DoubleMomentStatistics::combine
    );
For a non-double stream, you can use a collector: 
final Stream<SomeObject> stream = ...;
final DoubleMomentStatistics statistics = stream
    .collect(toDoubleMomentStatistics(v -> v.doubleValue()));
Since:
3.0
Version:
6.0
See Also:
Implementation Note:
This implementation is not thread safe. However, it is safe to use toDoubleMomentStatistics(ToDoubleFunction) on a parallel stream, because the parallel implementation of Stream.collect() provides the necessary partitioning, isolation, and merging of results for safe and efficient parallel execution.

  • Constructor Summary

    Constructors
    Constructor
    Description
    DoubleMomentStatistics()
    Create an empty moments object.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    accept(double value)
    Records a new value into the moment information
    DoubleMomentStatistics
    combine(DoubleMomentStatistics other)
    Combine two DoubleMoments statistic objects.
    long
    count()
    Returns the count of values recorded.
    double
    kurtosis()
    Return the kurtosis of values recorded, or Double.NaN if less than four values have been recorded.
    double
    max()
    Return the maximum value recorded, or Double.NEGATIVE_INFINITY if no values have been recorded.
    double
    mean()
    Return the arithmetic mean of values recorded, or Double.NaN if no values have been recorded.
    double
    min()
    Return the minimum value recorded, or Double.POSITIVE_INFINITY if no values have been recorded.
    DoubleMoments
    result()
     
    boolean
    sameState(DoubleMomentStatistics other)
    Compares the state of two DoubleMomentStatistics objects.
    double
    skewness()
    Return the skewness of values recorded, or Double.NaN if less than two values have been recorded.
    double
    sum()
    Return the sum of values recorded, or zero if no values have been recorded.
    DoubleMoments
    toDoubleMoments()
    Return a DoubleMoments object from the current statistics,
    static <T> Collector<T,?,DoubleMomentStatistics>
    toDoubleMomentStatistics(ToDoubleFunction<? super T> mapper)
    Return a Collector which applies a double-producing mapping function to each input element, and returns moments-statistics for the resulting values.
    String
    toString()
     
    double
    variance()
    Return the variance of values recorded, or Double.NaN if no values have been recorded.

    Methods inherited from class java.lang.Object

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

    Methods inherited from interface java.util.function.DoubleConsumer

    andThen

  • Constructor Details

  • Method Details

    • accept

      public void accept(double value)
      Records a new value into the moment information
      Specified by:
      accept in interface DoubleConsumer
      Parameters:
      value - the input value

    • combine

      public DoubleMomentStatistics combine(DoubleMomentStatistics other)
      Combine two DoubleMoments statistic objects.
      Parameters:
      other - the other DoubleMoments statistics to combine with this one.
      Returns:
      this statistics object
      Throws:
      NullPointerException - if the other statistical summary is null.

    • min

      public double min()
      Return the minimum value recorded, or Double.POSITIVE_INFINITY if no values have been recorded.
      Returns:
      the minimum value, or Double.POSITIVE_INFINITY if none

    • max

      public double max()
      Return the maximum value recorded, or Double.NEGATIVE_INFINITY if no values have been recorded.
      Returns:
      the maximum value, or Double.NEGATIVE_INFINITY if none

    • sum

      public double sum()
      Return the sum of values recorded, or zero if no values have been recorded.
      Returns:
      the sum of values, or zero if none

    • sameState

      public boolean sameState(DoubleMomentStatistics other)
      Compares the state of two DoubleMomentStatistics objects. This is a replacement for the Object.equals(Object) which is not advisable to implement for this mutable object. If two objects have the same state, it has still the same state when updated with the same value. 
      final DoubleMomentStatistics ds1 = ...;
final DoubleMomentStatistics ds2 = ...;

if (ds1.sameState(ds2)) {
    final double value = random.nextDouble();
    ds1.accept(value);
    ds2.accept(value);

    assert ds1.sameState(ds2);
    assert ds2.sameState(ds1);
    assert ds1.sameState(ds1);
}
      Parameters:
      other - the other object for the test
      Returns:
      true the this and the other objects have the same state, false otherwise
      Since:
      3.7

    • toDoubleMoments

      public DoubleMoments toDoubleMoments()
      Return a DoubleMoments object from the current statistics,
      Returns:
      a DoubleMoments object from the current statistics
      Since:
      3.9

    • result

      public DoubleMoments result()

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • toDoubleMomentStatistics

      public static <T> Collector<T,?,DoubleMomentStatistics> toDoubleMomentStatistics(ToDoubleFunction<? super T> mapper)
      Return a Collector which applies a double-producing mapping function to each input element, and returns moments-statistics for the resulting values. 
      final Stream<SomeObject> stream = ...;
final DoubleMomentStatistics statistics = stream
    .collect(toDoubleMomentStatistics(v -> v.doubleValue()));
      Type Parameters:
      T - the type of the input elements
      Parameters:
      mapper - a mapping function to apply to each element
      Returns:
      a Collector implementing the moments-statistics reduction
      Throws:
      NullPointerException - if the given mapper is null

    • count

      public long count()
      Returns the count of values recorded.
      Returns:
      the count of recorded values

    • mean

      public double mean()
      Return the arithmetic mean of values recorded, or Double.NaN if no values have been recorded.
      Returns:
      the arithmetic mean of values, or zero if none

    • variance

      public double variance()
      Return the variance of values recorded, or Double.NaN if no values have been recorded.
      Returns:
      the variance of values, or NaN if none

    • skewness

      public double skewness()
      Return the skewness of values recorded, or Double.NaN if less than two values have been recorded.
      Returns:
      the skewness of values, or NaN if less than two values have been recorded
      See Also:

    • kurtosis

      public double kurtosis()
      Return the kurtosis of values recorded, or Double.NaN if less than four values have been recorded.
      Returns:
      the kurtosis of values, or NaN if less than four values have been recorded
      See Also: