Package org.jfree.data.statistics

Class Statistics

java.lang.Object
org.jfree.data.statistics.Statistics
public abstract class Statistics
extends Object
A utility class that provides some simple statistical functions.

  • Constructor Summary

    Constructors
    Constructor Description
    Statistics()  

  • Method Summary

    Modifier and Type Method Description
    static double calculateMean​(Number[] values)
    Returns the mean of an array of numbers.
    static double calculateMean​(Collection values)
    Returns the mean of a collection of Number objects.
    static double calculateMedian​(List values)
    Calculates the median for a list of values (Number objects).
    static double calculateMedian​(List values, boolean copyAndSort)
    Calculates the median for a list of values (Number objects) that are assumed to be in ascending order.
    static double calculateMedian​(List values, int start, int end)
    Calculates the median for a sublist within a list of values (Number objects).
    static double calculateMedian​(List values, int start, int end, boolean copyAndSort)
    Calculates the median for a sublist within a list of values (Number objects).
    static double getAverage​(Number[] data)
    Deprecated.
    Renamed calculateMean().
    static double getCorrelation​(Number[] data1, Number[] data2)
    Calculates the correlation between two datasets.
    static double[] getLinearFit​(Number[] xData, Number[] yData)
    Fits a straight line to a set of (x, y) data, returning the slope and intercept.
    static double[][] getMovingAverage​(Number[] xData, Number[] yData, int period)
    Returns a data set for a moving average on the data set passed in.
    static double getSlope​(Number[] xData, Number[] yData)
    Finds the slope of a regression line using least squares.
    static double getStdDev​(Number[] data)
    Returns the standard deviation of a set of numbers.

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • Statistics

      public Statistics()

  • Method Details

    • calculateMean

      public static double calculateMean​(Number[] values)
      Returns the mean of an array of numbers.
      Parameters:
      values - the values (null permitted, returns Double.NaN).
      Returns:
      The mean.

    • calculateMean

      public static double calculateMean​(Collection values)
      Returns the mean of a collection of Number objects.
      Parameters:
      values - the values (null permitted, returns Double.NaN).
      Returns:
      The mean.

    • calculateMedian

      public static double calculateMedian​(List values)
      Calculates the median for a list of values (Number objects). The list of values will be sorted first.
      Parameters:
      values - the values.
      Returns:
      The median.

    • calculateMedian

      public static double calculateMedian​(List values, boolean copyAndSort)
      Calculates the median for a list of values (Number objects) that are assumed to be in ascending order.
      Parameters:
      values - the values.
      copyAndSort - a flag that controls whether the list of values is copied and sorted.
      Returns:
      The median.

    • calculateMedian

      public static double calculateMedian​(List values, int start, int end)
      Calculates the median for a sublist within a list of values (Number objects).
      Parameters:
      values - the values (in any order).
      start - the start index.
      end - the end index.
      Returns:
      The median.

    • calculateMedian

      public static double calculateMedian​(List values, int start, int end, boolean copyAndSort)
      Calculates the median for a sublist within a list of values (Number objects). The entire list will be sorted if the ascendingfalse.
      Parameters:
      values - the values.
      start - the start index.
      end - the end index.
      copyAndSort - a flag that that controls whether the list of values is copied and sorted.
      Returns:
      The median.

    • getStdDev

      public static double getStdDev​(Number[] data)
      Returns the standard deviation of a set of numbers.
      Parameters:
      data - the data.
      Returns:
      the standard deviation of a set of numbers.

    • getLinearFit

      public static double[] getLinearFit​(Number[] xData, Number[] yData)
      Fits a straight line to a set of (x, y) data, returning the slope and intercept.
      Parameters:
      xData - the x-data.
      yData - the y-data.
      Returns:
      a double array with the intercept in [0] and the slope in [1].

    • getSlope

      public static double getSlope​(Number[] xData, Number[] yData)
      Finds the slope of a regression line using least squares.
      Parameters:
      xData - an array of Numbers (the x values).
      yData - an array of Numbers (the y values).
      Returns:
      the slope.

    • getCorrelation

      public static double getCorrelation​(Number[] data1, Number[] data2)
      Calculates the correlation between two datasets. Both arrays should contain the same number of items. Null values are treated as zero.

      Information about the correlation calculation was obtained from: http://trochim.human.cornell.edu/kb/statcorr.htm

      Parameters:
      data1 - the first dataset.
      data2 - the second dataset.
      Returns:
      The correlation.

    • getMovingAverage

      public static double[][] getMovingAverage​(Number[] xData, Number[] yData, int period)
      Returns a data set for a moving average on the data set passed in.
      Parameters:
      xData - an array of the x data.
      yData - an array of the y data.
      period - the number of data points to average
      Returns:
      a double[][] the length of the data set in the first dimension, with two doubles for x and y in the second dimension

    • getAverage

      public static double getAverage​(Number[] data)
      Deprecated.
      Renamed calculateMean().
      Returns the average of a set of numbers.
      Parameters:
      data - the data.
      Returns:
      The average of a set of numbers.