Package net.sourceforge.jiu.util

Class Statistics

java.lang.Object
net.sourceforge.jiu.util.Statistics
public class Statistics extends Object
A number of static methods to compute statistical properties of an array of double values. Implements the computation of mean, variance and standard deviation for double values.
Since:
0.11.0
Author:
Marco Schmidt

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    Statistics()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static double
    computeMean(double[] values)
    Computes the mean value for the argument array.
    static double
    computeMean(double[] values, int offset, int number)
    Computes the mean value for some elements of the argument array.
    static double
    computeStandardDeviation(double[] values)
    Computes the standard deviation for the argument array of values.
    static double
    computeStandardDeviation(double[] values, double mean)
    Computes the standard deviation for the argument array of values.
    static double
    computeStandardDeviation(double[] values, int offset, int number)
    Computes the standard deviation for some of the argument array's values.
    static double
    computeStandardDeviation(double[] values, int offset, int number, double mean)
    Computes the standard deviation for some of the argument array's values.
    static double
    computeVariance(double[] values)
    Computes the variance for the argument array.
    static double
    computeVariance(double[] values, double mean)
    Computes the variance for some of the argument array's values.
    static double
    computeVariance(double[] values, int offset, int number)
    Computes the variance for some of the argument array's values.
    static double
    computeVariance(double[] values, int offset, int number, double mean)
    Computes the variance for some of the argument array's values.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Statistics

      private Statistics()

  • Method Details

    • computeMean

      public static double computeMean(double[] values)
      Computes the mean value for the argument array. Adds all values and divides them by the number of array elements.
      Parameters:
      values - double array on which the mean is to be determined
      Returns:
      computed mean value
      Throws:
      IllegalArgumentException - if the array has not at least one element

    • computeMean

      public static double computeMean(double[] values, int offset, int number)
      Computes the mean value for some elements of the argument array. Adds all values and divides them by the number of array elements.
      Parameters:
      values - array from which elements are read
      offset - index of the first element to be used
      number - number of elements to be used
      Returns:
      computed mean value
      Throws:
      IllegalArgumentException - if the array has not at least one element

    • computeStandardDeviation

      public static double computeStandardDeviation(double[] values)
      Computes the standard deviation for the argument array of values.
      Parameters:
      values - array from which elements are read
      Returns:
      computed standard deviation
      Throws:
      IllegalArgumentException - if the array has not at least two elements

    • computeStandardDeviation

      public static double computeStandardDeviation(double[] values, double mean)
      Computes the standard deviation for the argument array of values. Reuses the mean value for that argument which must have been computed before.
      Parameters:
      values - array from which elements are read
      mean - the mean value for the array, possibly computed with a call to computeMean(double[]).
      Returns:
      computed standard deviation
      Throws:
      IllegalArgumentException - if the array has not at least two elements

    • computeStandardDeviation

      public static double computeStandardDeviation(double[] values, int offset, int number)
      Computes the standard deviation for some of the argument array's values. If you already have computed a mean value using computeMean(double[], int, int), better call computeStandardDeviation(double[], int, int, double). Otherwise, this method has to compute mean again.
      Parameters:
      values - array from which elements are read
      offset - first element to be used
      number - number of elements used starting at values[offset]
      Returns:
      computed standard deviation
      Throws:
      IllegalArgumentException - if the array has not at least two elements

    • computeStandardDeviation

      public static double computeStandardDeviation(double[] values, int offset, int number, double mean)
      Computes the standard deviation for some of the argument array's values. Use this version of the method if you already have a mean value, otherwise this method must be computed again.
      Parameters:
      values - array from which elements are read
      offset - first element to be used
      number - number of elements used starting at values[offset]
      mean - value of the elements
      Returns:
      computed standard deviation
      Throws:
      IllegalArgumentException - if the array has not at least two elements

    • computeVariance

      public static double computeVariance(double[] values)
      Computes the variance for the argument array.
      Parameters:
      values - array from which elements are read
      Returns:
      variance for the array elements
      Throws:
      IllegalArgumentException - if the array has not at least two elements

    • computeVariance

      public static double computeVariance(double[] values, double mean)
      Computes the variance for some of the argument array's values.
      Parameters:
      values - array from which elements are read
      mean - the mean for the array elements
      Returns:
      variance for the array elements
      Throws:
      IllegalArgumentException - if the array has not at least two elements

    • computeVariance

      public static double computeVariance(double[] values, int offset, int number)
      Computes the variance for some of the argument array's values. If you already have computed a mean value using computeMean(double[], int, int), better call computeVariance(double[], int, int, double). Otherwise, this method has to compute mean again.
      Parameters:
      values - array from which elements are read
      offset - first element to be used
      number - number of elements used starting at values[offset]
      Returns:
      computed variance
      Throws:
      IllegalArgumentException - if the array has not at least two elements

    • computeVariance

      public static double computeVariance(double[] values, int offset, int number, double mean)
      Computes the variance for some of the argument array's values. Use this version of the method in case mean has already been computed.
      Parameters:
      values - array from which elements are read
      offset - first element to be used
      number - number of elements used starting at values[offset]
      mean - the mean for the array elements
      Returns:
      computed variance
      Throws:
      IllegalArgumentException - if the array has not at least two elements