be.ac.ulb.mlg.utils
Class MeasureUtils

java.lang.Object
  be.ac.ulb.mlg.utils.MeasureUtils

public final class MeasureUtils
extends Object

Field Summary

static double

EPSILON The precision value

Constructor Summary

MeasureUtils()

Method Summary

static void	bubbleSort(double[] comparable, int[] toSort) Apply bubble sort to sort indices (toSort) array based on the values (comparable) array which is also sorted
static boolean[]	constructComputable(double[][] vars) Compute the missing value array for the matrix (samples x vars)
static long	countOccurencies(double[][] vectors, double[] frequencies, boolean[] computable) Compute the number of occurrences of each distinct value with a precision of EPSILON (consider integers).
static long	countOccurencies(double[] vector, double[] frequencies, boolean hasMissing) Compute the number of occurrences of each distinct value with a precision of EPSILON (consider integers).
static double	fastMean(double[] vector, boolean hasMissing) Compute the mean by summing all elements of the vector in left-right manner
static double	fastMean(double[] vector, boolean[] computable) Compute the mean by summing all elements of the vector in left-right manner
static double	fastSum(double[] vector, boolean[] computable) Compute the sum by summing all elements of the vector in left-right manner
static double	log(double value) Compute the log, base e but return 0 if the value is less than EPSILON
static int	naturalRank(boolean[] computable, double[] vector, double[] ranks) Computed the natural rank of values
static int	naturalRank(boolean[] computable, double[] vector, double[] ranks, int[] untied) Computed the natural rank of values
static double	sqrt(double value) Compute the square root value by using the formula exp(0.5*log(x)) <=> sqrt(x) in order to avoid underflow.

Methods inherited from class java.lang.Object

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

Field Detail

EPSILON

public static final double EPSILON

The precision value

See Also:

Constant Field Values

Constructor Detail

MeasureUtils

public MeasureUtils()

Method Detail

fastSum

public static final double fastSum(double[] vector,
                                   boolean[] computable)

Compute the sum by summing all elements of the vector in left-right manner

Parameters:

vector - The data vector

computable - The boolean array which specifies if indexes must be taken

Returns:

The mean of the data vector

fastMean

public static final double fastMean(double[] vector,
                                    boolean[] computable)

Compute the mean by summing all elements of the vector in left-right manner

Parameters:

vector - The data vector

computable - The boolean array which specifies if indexes must be taken

Returns:

The mean of the data vector

fastMean

public static final double fastMean(double[] vector,
                                    boolean hasMissing)

Compute the mean by summing all elements of the vector in left-right manner

Parameters:

vector - The data vector

hasMissing - True if missing values are contained in the vector

Returns:

The mean of the data vector

bubbleSort

public static void bubbleSort(double[] comparable,
                              int[] toSort)

Apply bubble sort to sort indices (toSort) array based on the values (comparable) array which is also sorted

Parameters:

comparable - The value array

toSort - The indices array

naturalRank

public static int naturalRank(boolean[] computable,
                              double[] vector,
                              double[] ranks)

Computed the natural rank of values

Parameters:

computable - The boolean array which specifies if indexes must be taken

vector - The data vector (values) to rank

ranks - The rank destination vector (must have the same size that the vector argument)

Returns:

The number of tied values

naturalRank

public static int naturalRank(boolean[] computable,
                              double[] vector,
                              double[] ranks,
                              int[] untied)

Computed the natural rank of values

Parameters:

computable - The boolean array which specifies if indexes must be taken

vector - The data vector (values) to rank

ranks - The rank destination vector (must have the same size that the vector argument)

untied - Copy the natural rank attribution without dealing with ties (sort index from 1 to length)

Returns:

The number of tied values

constructComputable

public static boolean[] constructComputable(double[][] vars)

Compute the missing value array for the matrix (samples x vars)

Parameters:

vars - The matrix

Returns:

The missing value array: true if computable, false if missing

countOccurencies

public static final long countOccurencies(double[] vector,
                                          double[] frequencies,
                                          boolean hasMissing)

Compute the number of occurrences of each distinct value with a precision of EPSILON (consider integers).

Parameters:

vector - The vector of values

frequencies - The occurrences matrix, 0 for NaN if hasMissing is true, 0 for redundant value (because n times a same distinct value result in a occurrence value of n)

hasMissing - if true, check for missing value in order to ignore them

Returns:

The number of distinct values for the first part of the long (<<32) and the number of values for the second part, (avoiding missing if hasMissing)

countOccurencies

public static final long countOccurencies(double[][] vectors,
                                          double[] frequencies,
                                          boolean[] computable)

Compute the number of occurrences of each distinct value with a precision of EPSILON (consider integers).

Parameters:

vectors - The matrix of values, have to be composed of two vectors of the same size

frequencies - The occurrences matrix, 0 for NaN if hasMissing is true, 0 for redundant value (because n times a same distinct value result in a occurrence value of n)

computable - The vector of missing value for the vector indexes

Returns:

The number of distinct values for the first part of the long (<<32) and the number of values for the second part, (avoiding missing if hasMissing)

sqrt

public static double sqrt(double value)

Compute the square root value by using the formula exp(0.5*log(x)) <=> sqrt(x) in order to avoid underflow.

Parameters:

value - The value for which the function compute the square root

Returns:

The square root of the given value

log

public static double log(double value)

Compute the log, base e but return 0 if the value is less than EPSILON

Parameters:

value - The value for which the function compute the square root

Returns:

The square root of the given value