org.jfree.data
Class Statistics

java.lang.Object
  |
  +--org.jfree.data.Statistics

public class Statistics

extends java.lang.Object

A utility class that provides some simple statistical functions.

Author:

Matthew Wright

Constructor Summary

Statistics()

Method Summary

static double	getAverage(java.lang.Number[] data) Returns the average of a set of numbers.
static double	getCorrelation(java.lang.Number[] data1, java.lang.Number[] data2) Calculates the correlation between two datasets.
static double[]	getLinearFit(java.lang.Number[] xData, java.lang.Number[] yData) Fits a straight line to a set of (x, y) data, returning the slope and intercept.
static double[][]	getMovingAverage(java.lang.Number[] xData, java.lang.Number[] yData, int period) Returns a data set for a moving average on the data set passed in.
static double	getSlope(java.lang.Number[] xData, java.lang.Number[] yData) Finds the slope of a regression line using least squares.
static double	getStdDev(java.lang.Number[] data) Returns the standard deviation of a set of numbers.

Methods inherited from class java.lang.Object

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

Constructor Detail

Statistics

public Statistics()

Method Detail

getAverage

public static double getAverage(java.lang.Number[] data)

Returns the average of a set of numbers.

Parameters:

data - the data.

Returns:

the average of a set of numbers.

getStdDev

public static double getStdDev(java.lang.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(java.lang.Number[] xData,
                                    java.lang.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(java.lang.Number[] xData,
                              java.lang.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(java.lang.Number[] data1,
                                    java.lang.Number[] data2)

Calculates the correlation between two datasets.

Parameters:

data1 - the first dataset.

data2 - the second dataset.

Returns:

the correlation between two datasets.

getMovingAverage

public static double[][] getMovingAverage(java.lang.Number[] xData,
                                          java.lang.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