Package org.apache.commons.statistics.descriptive

Class DoubleStatistics

java.lang.Object
org.apache.commons.statistics.descriptive.DoubleStatistics
All Implemented Interfaces:
DoubleConsumer
public final class DoubleStatistics extends Object implements DoubleConsumer
Statistics for double values.

This class provides combinations of individual statistic implementations in the org.apache.commons.statistics.descriptive package.

Supports up to 263 (exclusive) observations. This implementation does not check for overflow of the count.

Since:
1.1

  • Method Details

    • of

      public static DoubleStatistics of(Statistic... statistics)
      Returns a new instance configured to compute the specified statistics.

      The statistics will be empty and so will return the default values for each computed statistic.

      Parameters:
      statistics - Statistics to compute.
      Returns:
      the instance
      Throws:
      IllegalArgumentException - if there are no statistics to compute.

    • of

      public static DoubleStatistics of(Set<Statistic> statistics, double... values)
      Returns a new instance configured to compute the specified statistics populated using the input values.

      Use this method to create an instance populated with a (variable) array of double[] data: 

       DoubleStatistics stats = DoubleStatistics.of(
     EnumSet.of(Statistic.MIN, Statistic.MAX),
     1, 1, 2, 3, 5, 8, 13);
      Parameters:
      statistics - Statistics to compute.
      values - Values.
      Returns:
      the instance
      Throws:
      IllegalArgumentException - if there are no statistics to compute.

    • ofRange

      public static DoubleStatistics ofRange(Set<Statistic> statistics, double[] values, int from, int to)
      Returns a new instance configured to compute the specified statistics populated using the specified range of values.

      Use this method to create an instance populated with part of an array of double[] data, e.g. to use the first half of the data: 

       double[] data = ...
 DoubleStatistics stats = DoubleStatistics.of(
     EnumSet.of(Statistic.MIN, Statistic.MAX),
     data, 0, data.length / 2);
      Parameters:
      statistics - Statistics to compute.
      values - Values.
      from - Inclusive start of the range.
      to - Exclusive end of the range.
      Returns:
      the instance
      Throws:
      IllegalArgumentException - if there are no statistics to compute.
      IndexOutOfBoundsException - if the sub-range is out of bounds
      Since:
      1.2

    • builder

      public static DoubleStatistics.Builder builder(Statistic... statistics)
      Returns a new builder configured to create instances to compute the specified statistics.

      Use this method to create an instance populated with an array of double[] data using the DoubleStatistics.Builder.build(double...) method: 

       double[] data = ...
 DoubleStatistics stats = DoubleStatistics.builder(
     Statistic.MIN, Statistic.MAX, Statistic.VARIANCE)
     .build(data);

      The builder can be used to create multiple instances of DoubleStatistics to be used in parallel, or on separate arrays of double[] data. These may be combined. For example: 

       double[][] data = ...
 DoubleStatistics.Builder builder = DoubleStatistics.builder(
     Statistic.MIN, Statistic.MAX, Statistic.VARIANCE);
 DoubleStatistics stats = Arrays.stream(data)
     .parallel()
     .map(builder::build)
     .reduce(DoubleStatistics::combine)
     .get();

      The builder can be used to create a Collector for repeat use on multiple data: 

      
 DoubleStatistics.Builder builder = DoubleStatistics.builder(
     Statistic.MIN, Statistic.MAX, Statistic.VARIANCE);
 Collector<double[], DoubleStatistics, DoubleStatistics> collector =
     Collector.of(builder::build,
                  (s, d) -> s.combine(builder.build(d)),
                  DoubleStatistics::combine);

 // Repeated
 double[][] data = ...
 DoubleStatistics stats = Arrays.stream(data).collect(collector);
      Parameters:
      statistics - Statistics to compute.
      Returns:
      the builder
      Throws:
      IllegalArgumentException - if there are no statistics to compute.

    • accept

      public void accept(double value)
      Updates the state of the statistics to reflect the addition of value.
      Specified by:
      accept in interface DoubleConsumer
      Parameters:
      value - Value.

    • getCount

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

    • isSupported

      public boolean isSupported(Statistic statistic)
      Check if the specified statistic is supported.

      Note: This method will not return false if the argument is null.

      Parameters:
      statistic - Statistic.
      Returns:
      true if supported
      Throws:
      NullPointerException - if the statistic is null
      See Also:

    • getAsDouble

      public double getAsDouble(Statistic statistic)
      Gets the value of the specified statistic as a double.
      Parameters:
      statistic - Statistic.
      Returns:
      the value
      Throws:
      IllegalArgumentException - if the statistic is not supported
      See Also:

    • getResult

      public StatisticResult getResult(Statistic statistic)
      Gets a supplier for the value of the specified statistic.

      The returned function will supply the correct result after calls to accept or combine further values into this instance.

      This method can be used to perform a one-time look-up of the statistic function to compute statistics as values are dynamically added.

      Parameters:
      statistic - Statistic.
      Returns:
      the supplier
      Throws:
      IllegalArgumentException - if the statistic is not supported
      See Also:

    • combine

      public DoubleStatistics combine(DoubleStatistics other)
      Combines the state of the other statistics into this one. Only this instance is modified by the combine operation.

      The other instance must be compatible. This is true if the other instance returns true for isSupported(Statistic) for all values of the Statistic enum which are supported by this instance.

      Note that this operation is not symmetric. It may be possible to perform a.combine(b) but not b.combine(a). In the event that the other instance is not compatible then an exception is raised before any state is modified.

      Parameters:
      other - Another set of statistics to be combined.
      Returns:
      this instance after combining other.
      Throws:
      IllegalArgumentException - if the other is not compatible

    • setConfiguration

      public DoubleStatistics setConfiguration(StatisticsConfiguration v)
      Sets the statistics configuration.

      These options only control the final computation of statistics. The configuration will not affect compatibility between instances during a combine operation.

      Note: These options will affect any future computation of statistics. Supplier functions that have been previously created will not be updated with the new configuration.

      Parameters:
      v - Value.
      Returns:
      this instance
      Throws:
      NullPointerException - if the value is null
      See Also: