Package org.apache.commons.math4.legacy.stat.descriptive.summary

Class Sum

  • All Implemented Interfaces:
    MathArrays.Function, StorelessUnivariateStatistic, UnivariateStatistic
    public class Sum
extends AbstractStorelessUnivariateStatistic
    Returns the sum of the available values.

    If there are no values in the dataset, then 0 is returned. If any of the values are NaN, then NaN is returned.

    Note that this implementation is not synchronized. If multiple threads access an instance of this class concurrently, and at least one of the threads invokes the increment() or clear() method, it must be synchronized externally.

    • Constructor Summary

      Constructors 
      Constructor Description
      Sum()
      Create a Sum instance.
      Sum​(Sum original)
      Copy constructor, creates a new Sum identical to the original.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      void clear()
      Clears the internal state of the Statistic.
      Sum copy()
      Returns a copy of the statistic with the same internal state.
      static void copy​(Sum source, Sum dest)
      Copies source to dest.
      double evaluate​(double[] values, double[] weights)
      The weighted sum of the entries in the input array.
      double evaluate​(double[] values, double[] weights, int begin, int length)
      The weighted sum of the entries in the specified portion of the input array, or 0 if the designated subarray is empty.
      double evaluate​(double[] values, int begin, int length)
      The sum of the entries in the specified portion of the input array, or 0 if the designated subarray is empty.
      long getN()
      Returns the number of values that have been added.
      double getResult()
      Returns the current value of the Statistic.
      void increment​(double d)
      Updates the internal state of the statistic to reflect the addition of the new value.

    • Constructor Detail

      • Sum

        public Sum()
        Create a Sum instance.

    • Method Detail

      • getN

        public long getN()
        Returns the number of values that have been added.
        Returns:
        the number of values.

      • evaluate

        public double evaluate​(double[] values,
                       double[] weights,
                       int begin,
                       int length)
                throws MathIllegalArgumentException
        The weighted sum of the entries in the specified portion of the input array, or 0 if the designated subarray is empty.

        Throws MathIllegalArgumentException if any of the following are true:

        • the values array is null
        • the weights array is null
        • the weights array does not have the same length as the values array
        • the weights array contains one or more infinite values
        • the weights array contains one or more NaN values
        • the weights array contains negative values
        • the start and length arguments do not determine a valid array

        Uses the formula, 

            weighted sum = Σ(values[i] * weights[i])
        Parameters:
        values - the input array
        weights - the weights array
        begin - index of the first array element to include
        length - the number of elements to include
        Returns:
        the sum of the values or 0 if length = 0
        Throws:
        MathIllegalArgumentException - if the parameters are not valid
        Since:
        2.1

      • evaluate

        public double evaluate​(double[] values,
                       double[] weights)
                throws MathIllegalArgumentException
        The weighted sum of the entries in the input array.

        Throws MathIllegalArgumentException if any of the following are true:

        • the values array is null
        • the weights array is null
        • the weights array does not have the same length as the values array
        • the weights array contains one or more infinite values
        • the weights array contains one or more NaN values
        • the weights array contains negative values

        Uses the formula, 

            weighted sum = Σ(values[i] * weights[i])
        Parameters:
        values - the input array
        weights - the weights array
        Returns:
        the sum of the values or Double.NaN if length = 0
        Throws:
        MathIllegalArgumentException - if the parameters are not valid
        Since:
        2.1

      • copy

        public static void copy​(Sum source,
                        Sum dest)
                 throws NullArgumentException
        Copies source to dest.

        Neither source nor dest can be null.

        Parameters:
        source - Sum to copy
        dest - Sum to copy to
        Throws:
        NullArgumentException - if either source or dest is null