net.librec.math.algorithm

Class Stats

java.lang.Object

net.librec.math.algorithm.Stats

public class Stats
extends java.lang.Object

Author:

Guo Guibing

Constructor Summary

Constructors

Constructor and Description
Stats()

Method Summary

Methods

Modifier and Type	Method and Description
static double	average(java.util.List<java.lang.Double> data, java.util.List<java.lang.Double> weights) Return weighted average value of data and weights.
static double	hMean(double a, double b) Return harmonic mean.
static double[]	max(double[] data) Find out the maximum element and its index of an array
static int[]	max(int[] data) Find out the maximum element and its index of an array.
static double	mean(java.util.Collection<? extends java.lang.Number> data) Return mean value of a sample.
static double	mean(double[] data) reference: http://www.weibull.com/DOEWeb/unbiased_and_biased_estimators.htm
static double	median(java.util.Collection<? extends java.lang.Number> data) Calculate the median value of a data collection, Note that the values of doulbe.NaN will be ignored silently
static double	median(double[] data) Calculate the median value of an array, Note that the values of doulbe.NaN will be ignored silently.
static double[]	min(double[] data) Find out the minimum element and its index of an array.
static int[]	min(int[] data) Find out the minimum element and its index of an array.
static double	mode(double[] data)
static double	sd(java.util.Collection<? extends java.lang.Number> data) Calculate the standard deviation.
static double	sd(java.util.Collection<? extends java.lang.Number> data, double mean) Calculate the standard deviation.
static double	sd(double[] data) Calculate a sample's standard deviation.
static double	sd(double[] data, double mean) Calculate a sample's standard deviation.
static double	sum(java.util.Collection<? extends java.lang.Number> data)
static double	sum(double[] data)
static int	sum(int n) The sum from 1 to n.
static int	sum(int[] data)
static double	sumSquare(int n) The sum from 1^2 to n^2, with the largest value to n^3/3
static double	var(double[] data) Calculate a sample's variance.
static double	var(double[] data, double mean) Calculate a sample's variance
static double	weightedcMean(double[] a, double[] w)

Methods inherited from class java.lang.Object

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

Constructor Detail

Stats

public Stats()

Method Detail

mean

public static double mean(java.util.Collection<? extends java.lang.Number> data)

Return mean value of a sample.

Parameters:

data - the set to sample from

Returns:

mean value of a sample

hMean

public static double hMean(double a,
           double b)

Return harmonic mean.

Parameters:

a - parameter of the function

b - parameter of the function

Returns:

harmonic mean

mean

public static double mean(double[] data)

reference: http://www.weibull.com/DOEWeb/unbiased_and_biased_estimators.htm

Notes: the sample mean and population mean is estimated in the same way.

Parameters:

data - the set to sample from

Returns:

mean value of a sample

mode

public static double mode(double[] data)

weightedcMean

public static double weightedcMean(double[] a,
                   double[] w)

average

public static double average(java.util.List<java.lang.Double> data,
             java.util.List<java.lang.Double> weights)

Return weighted average value of data and weights.

Parameters:

data - data set

weights - weight for the data

Returns:

weighted average value of data and weights

median

public static double median(double[] data)

Calculate the median value of an array, Note that the values of doulbe.NaN will be ignored silently.

Parameters:

data - an array

Returns:

median value of an array,

median

public static double median(java.util.Collection<? extends java.lang.Number> data)

Calculate the median value of a data collection, Note that the values of doulbe.NaN will be ignored silently

Parameters:

data - a data collection

Returns:

the median value of the data collection

var

public static double var(double[] data)

Calculate a sample's variance.

Parameters:

data - a data array

Returns:

variance of the sample

var

public static double var(double[] data,
         double mean)

Calculate a sample's variance

refers to: http://www.weibull.com/DOEWeb/unbiased_and_biased_estimators.htm, for an explanation why the denominator is (n-1) rather than n.

Parameters:

data - a data array

mean - mean of the data array

Returns:

the sample's variance

sd

public static double sd(java.util.Collection<? extends java.lang.Number> data)

Calculate the standard deviation.

Parameters:

data - a data collection

Returns:

standard deviation of the collection

sd

public static double sd(java.util.Collection<? extends java.lang.Number> data,
        double mean)

Calculate the standard deviation.

Parameters:

data - a data collection

mean - mean of the collection

Returns:

standard deviation of the collection

sd

public static double sd(double[] data)

Calculate a sample's standard deviation.

Parameters:

data - a data array

Returns:

sample's standard deviation

sd

public static double sd(double[] data,
        double mean)

Calculate a sample's standard deviation.

Parameters:

data - a data array

mean - mean of the data

Returns:

sample's standard deviation

sum

public static double sum(double[] data)

sum

public static double sum(java.util.Collection<? extends java.lang.Number> data)

sum

public static int sum(int[] data)

sum

public static int sum(int n)

The sum from 1 to n.

Parameters:

n - max of the sum sequence

Returns:

sum of the sequence 1 to n

sumSquare

public static double sumSquare(int n)

The sum from 1^2 to n^2, with the largest value to n^3/3

Parameters:

n - parameter n of the function

Returns:

sum from 1^2 to n^2, with the largest value to n^3/3

max

public static double[] max(double[] data)

Find out the maximum element and its index of an array

Parameters:

data - a data array

Returns:

the maximum element and its index of an array

max

public static int[] max(int[] data)

Find out the maximum element and its index of an array.

Parameters:

data - a data array

Returns:

the maximum element and its index of an array

min

public static int[] min(int[] data)

Find out the minimum element and its index of an array.

Parameters:

data - a data array

Returns:

the minimum element and its index of an array.

min

public static double[] min(double[] data)

Find out the minimum element and its index of an array.

Parameters:

data - a data array

Returns:

the minimum element and its index of an array.