papaya
Class Descriptive.Mean

java.lang.Object
  papaya.Descriptive.Mean

Enclosing class:

Descriptive

public static class Descriptive.Mean
extends Object

Contains methods for computing the arithmetic, geometric, harmonic, trimmed, and winsorized means (among others).

Method Summary

static float	arithmetic(float[] data) Returns the arithmetic mean of a data sequence; That is Sum( data[i] ) / data.length .
static float[]	columnMean(float[][] data) Returns an array containing the arithmetic mean of each column of the input matrix.
static float	geometric(float[] data) Returns the geometric mean of a data sequence.
static float	geometric(int size, float sumOfLogarithms) Returns the geometric mean of a data sequence.
static float	harmonic(float[] data) Returns the harmonic mean of a data sequence as Sum( 1.0 / data[i]).
static float	harmonic(int size, float sumOfInversions) Returns the harmonic mean of a data sequence.
static float[]	rowMean(float[][] data) Returns an array containing the arithmetic mean of each row of the input matrix.
static float	trimmed(float[] sortedData, float mean, int left, int right) Returns the trimmed arithmetic mean of a sorted data sequence.
static float	winsorized(float[] sortedData, float mean, int left, int right) Returns the winsorized mean of a sorted data sequence.

Methods inherited from class java.lang.Object

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

Method Detail

columnMean

public static float[] columnMean(float[][] data)

Returns an array containing the arithmetic mean of each column of the input matrix.

rowMean

public static float[] rowMean(float[][] data)

Returns an array containing the arithmetic mean of each row of the input matrix.

arithmetic

public static float arithmetic(float[] data)

Returns the arithmetic mean of a data sequence; That is Sum( data[i] ) / data.length .

geometric

public static float geometric(int size,
                              float sumOfLogarithms)

Returns the geometric mean of a data sequence. Note that for a geometric mean to be meaningful, the minimum of the data sequence must not be less or equal to zero.
The geometric mean is given by pow( Product( data[i] ), 1/size) which is equivalent to Math.exp( Sum( Log(data[i]) ) / size).

The latter version is used here is the former easily results in overflows.

geometric

public static float geometric(float[] data)

Returns the geometric mean of a data sequence. Note that for a geometric mean to be meaningful, the minimum of the data sequence must not be less or equal to zero.
The geometric mean is given by pow( Product( data[i] ), 1/data.size()). This method tries to avoid overflows at the expense of an equivalent but somewhat slow definition: geometricMean = Math.exp( Sum( Log(data[i]) ) / size).

harmonic

public static float harmonic(int size,
                             float sumOfInversions)

Returns the harmonic mean of a data sequence.

Parameters:

size - the number of elements in the data sequence.

sumOfInversions - Sum( 1.0 / data[i]).

harmonic

public static float harmonic(float[] data)

Returns the harmonic mean of a data sequence as Sum( 1.0 / data[i]).

Parameters:

data - array

trimmed

public static float trimmed(float[] sortedData,
                            float mean,
                            int left,
                            int right)

Returns the trimmed arithmetic mean of a sorted data sequence.

Parameters:

sortedData - the data sequence; must be sorted ascending.

mean - the mean of the (full) sorted data sequence.

left - the number of leading elements to trim.

right - the number of trailing elements to trim.

winsorized

public static float winsorized(float[] sortedData,
                               float mean,
                               int left,
                               int right)

Returns the winsorized mean of a sorted data sequence.

Parameters:

sortedData - the data sequence; must be sorted ascending.

mean - the mean of the (full) sorted data sequence.

left - the number of leading elements to trim.

right - the number of trailing elements to trim.