Class DataSet

java.lang.Object
org.uncommons.maths.statistics.DataSet

public class DataSet extends Object
Utility class for calculating statistics for a finite data set.
See Also:
  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private double[]
     
    private int
     
    private static final int
     
    private static final double
     
    private double
     
    private double
     
    private double
     
    private double
     
    private double
     
  • Constructor Summary

    Constructors
    Constructor
    Description
    Creates an empty data set with a default initial capacity.
    DataSet(double[] dataSet)
    Creates a data set and populates it with the specified values.
    DataSet(int capacity)
    Creates an empty data set with the specified initial capacity.
  • Method Summary

    Modifier and Type
    Method
    Description
    void
    addValue(double value)
    Adds a single value to the data set and updates any statistics that are calculated cumulatively.
    private void
     
    final double
     
    final double
    The arithemthic mean of an n-element set is the sum of all the elements divided by n.
    final double
    The geometric mean of an n-element set is the nth-root of the product of all the elements.
    final double
    The harmonic mean of an n-element set is n divided by the sum of the reciprocals of the values (where the reciprocal of a value x is 1/x).
    final double
     
    final double
    Calculates the mean absolute deviation of the data set.
    final double
    Determines the median value of the data set.
    final double
     
    final double
     
    final double
    The sample standard deviation is the square root of the sample variance.
    final double
    Calculates the variance (a measure of statistical dispersion) of the data set.
    final int
    Returns the number of values in this data set.
    final double
    The standard deviation is the square root of the variance.
    final double
    Calculates the variance (a measure of statistical dispersion) of the data set.
    private double
    Helper method for variance calculations.
    private void
     

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Field Details

    • DEFAULT_CAPACITY

      private static final int DEFAULT_CAPACITY
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    • GROWTH_RATE

      private static final double GROWTH_RATE
      See Also:
    • dataSet

      private double[] dataSet
    • dataSetSize

      private int dataSetSize
    • total

      private double total
    • product

      private double product
    • reciprocalSum

      private double reciprocalSum
    • minimum

      private double minimum
    • maximum

      private double maximum
  • Constructor Details

    • DataSet

      public DataSet()
      Creates an empty data set with a default initial capacity.
    • DataSet

      public DataSet(int capacity)
      Creates an empty data set with the specified initial capacity.
      Parameters:
      capacity - The initial capacity for the data set (this number of values will be able to be added without needing to resize the internal data storage).
    • DataSet

      public DataSet(double[] dataSet)
      Creates a data set and populates it with the specified values.
      Parameters:
      dataSet - The values to add to this data set.
  • Method Details

    • addValue

      public void addValue(double value)
      Adds a single value to the data set and updates any statistics that are calculated cumulatively.
      Parameters:
      value - The value to add.
    • updateStatsWithNewValue

      private void updateStatsWithNewValue(double value)
    • assertNotEmpty

      private void assertNotEmpty()
    • getSize

      public final int getSize()
      Returns the number of values in this data set.
      Returns:
      The size of the data set.
    • getMinimum

      public final double getMinimum()
      Returns:
      The smallest value in the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      Since:
      1.0.1
    • getMaximum

      public final double getMaximum()
      Returns:
      The biggest value in the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      Since:
      1.0.1
    • getMedian

      public final double getMedian()
      Determines the median value of the data set.
      Returns:
      If the number of elements is odd, returns the middle element. If the number of elements is even, returns the midpoint of the two middle elements.
      Since:
      1.0.1
    • getAggregate

      public final double getAggregate()
      Returns:
      The sum of all values.
      Throws:
      EmptyDataSetException - If the data set is empty.
    • getProduct

      public final double getProduct()
      Returns:
      The product of all values.
      Throws:
      EmptyDataSetException - If the data set is empty.
    • getArithmeticMean

      public final double getArithmeticMean()
      The arithemthic mean of an n-element set is the sum of all the elements divided by n. The arithmetic mean is often referred to simply as the "mean" or "average" of a data set.
      Returns:
      The arithmetic mean of all elements in the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      See Also:
    • getGeometricMean

      public final double getGeometricMean()
      The geometric mean of an n-element set is the nth-root of the product of all the elements. The geometric mean is used for finding the average factor (e.g. an average interest rate).
      Returns:
      The geometric mean of all elements in the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      See Also:
    • getHarmonicMean

      public final double getHarmonicMean()
      The harmonic mean of an n-element set is n divided by the sum of the reciprocals of the values (where the reciprocal of a value x is 1/x). The harmonic mean is used to calculate an average rate (e.g. an average speed).
      Returns:
      The harmonic mean of all the elements in the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      Since:
      1.1
      See Also:
    • getMeanDeviation

      public final double getMeanDeviation()
      Calculates the mean absolute deviation of the data set. This is the average (absolute) amount that a single value deviates from the arithmetic mean.
      Returns:
      The mean absolute deviation of the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      See Also:
    • getVariance

      public final double getVariance()
      Calculates the variance (a measure of statistical dispersion) of the data set. There are different measures of variance depending on whether the data set is itself a finite population or is a sample from some larger population. For large data sets the difference is negligible. This method calculates the population variance.
      Returns:
      The population variance of the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      See Also:
    • sumSquaredDiffs

      private double sumSquaredDiffs()
      Helper method for variance calculations.
      Returns:
      The sum of the squares of the differences between each value and the arithmetic mean.
      Throws:
      EmptyDataSetException - If the data set is empty.
    • getStandardDeviation

      public final double getStandardDeviation()
      The standard deviation is the square root of the variance. This method calculates the population standard deviation as opposed to the sample standard deviation. For large data sets the difference is negligible.
      Returns:
      The standard deviation of the population.
      Throws:
      EmptyDataSetException - If the data set is empty.
      See Also:
    • getSampleVariance

      public final double getSampleVariance()
      Calculates the variance (a measure of statistical dispersion) of the data set. There are different measures of variance depending on whether the data set is itself a finite population or is a sample from some larger population. For large data sets the difference is negligible. This method calculates the sample variance.
      Returns:
      The sample variance of the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      See Also:
    • getSampleStandardDeviation

      public final double getSampleStandardDeviation()
      The sample standard deviation is the square root of the sample variance. For large data sets the difference between sample standard deviation and population standard deviation is negligible.
      Returns:
      The sample standard deviation of the data set.
      Throws:
      EmptyDataSetException - If the data set is empty.
      See Also: