org.openimaj.math.util

Class FloatArrayStatsUtils

java.lang.Object

org.openimaj.math.util.FloatArrayStatsUtils

public class FloatArrayStatsUtils
extends Object

Some basic statistical operations on float arrays

Author:

Sina Samangooei (ss@ecs.soton.ac.uk)

Constructor Summary

Constructors

Constructor and Description
FloatArrayStatsUtils()

Method Summary

Modifier and Type	Method and Description
static float	mean(float[] arr) Find the mean of a single dimensional float array.
static float	mean(float[][] arr) Calculate the mean of a two dimensional float array.
static float	median(float[] arr) Calculate the median of the given array.
static float	median(float[] arr, int start, int stop) Calculate the median of the given sub-array.
static float	std(float[] arr) Calculate the standard deviation of a 1D array.
static float	std(float[][] arr) Calculate the standard deviation of a 2D array.
static float	sum(float[] arr) Calculate the sum of a 1D array.
static float	sum(float[][] arr) Calculate the sum of a 2D array.
static float	sumAbs(float[] arr) Calculate the sum the absolute values of a 1D array.
static float	sumAbs(float[][] arr) Calculate the sum of the absolute values of a 2D array.
static float	sumSq(float[] arr) Calculate the sum the squared values of a 1D array.
static float	sumSq(float[][] arr) Calculate the sum of the squared values of a 2D array.
static float	var(float[] arr) Calculate the variance of a one dimensional float array.
static float	var(float[][] arr) Calculate the variance of a one dimensional float array.

Methods inherited from class java.lang.Object

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

Constructor Detail

FloatArrayStatsUtils

public FloatArrayStatsUtils()

Method Detail

mean

public static float mean(float[] arr)

Find the mean of a single dimensional float array. returns 0 if the array is empty.

Parameters:

arr -

Returns:

the mean

mean

public static float mean(float[][] arr)

Calculate the mean of a two dimensional float array. returns 0 if the array is empty.

Parameters:

arr -

Returns:

the mean

var

public static float var(float[] arr)

Calculate the variance of a one dimensional float array. If the length of the array is less than 2, variance is 0.

Parameters:

arr -

Returns:

the variance

var

public static float var(float[][] arr)

Calculate the variance of a one dimensional float array. If the length of the array is less than 2, variance is 0.

Parameters:

arr -

Returns:

the variance

std

public static float std(float[][] arr)

Calculate the standard deviation of a 2D array. Calls var(float[][]) and does a Math.sqrt.

Parameters:

arr -

Returns:

the standard deviation

std

public static float std(float[] arr)

Calculate the standard deviation of a 1D array. Calls var(float[]) and does a Math.sqrt.

Parameters:

arr -

Returns:

the standard deviation

sum

public static float sum(float[][] arr)

Calculate the sum of a 2D array.

Parameters:

arr -

Returns:

the sum

sum

public static float sum(float[] arr)

Calculate the sum of a 1D array.

Parameters:

arr -

Returns:

the sum

sumSq

public static float sumSq(float[][] arr)

Calculate the sum of the squared values of a 2D array.

Parameters:

arr -

Returns:

sum of squares

sumSq

public static float sumSq(float[] arr)

Calculate the sum the squared values of a 1D array.

Parameters:

arr -

Returns:

sum of squares

sumAbs

public static float sumAbs(float[][] arr)

Calculate the sum of the absolute values of a 2D array.

Parameters:

arr -

Returns:

the sum absolute values

sumAbs

public static float sumAbs(float[] arr)

Calculate the sum the absolute values of a 1D array.

Parameters:

arr -

Returns:

the sum absolute values

median

public static float median(float[] arr)

Calculate the median of the given array. Uses the quick select algorithm (ArrayUtils.quickSelect(float[], int)).

Parameters:

arr - the array

Returns:

the median value

median

public static float median(float[] arr,
                           int start,
                           int stop)

Calculate the median of the given sub-array. Uses the quick select algorithm (ArrayUtils.quickSelect(float[], int, int, int)).

Parameters:

arr - the array

start - starting point in the array (inclusive)

stop - stopping point in the array (exclusive)

Returns:

the median value