opennlp.tools.ml

Class ArrayMath

java.lang.Object

opennlp.tools.ml.ArrayMath

Direct Known Subclasses:

ArrayMath

public class ArrayMath
extends Object

Utility class for simple vector arithmetic.

Constructor Summary

Constructors

Constructor and Description
ArrayMath()

Method Summary

Modifier and Type	Method and Description
static int	argmax(double[] x) Find index of maximum element in the vector x
static double	innerProduct(double[] vecA, double[] vecB)
static double	invL2norm(double[] v) Inverse L2-norm
static double	l1norm(double[] v) L1-norm
static double	l2norm(double[] v) L2-norm
static double	logSumOfExps(double[] x) Computes \log(\sum_{i=1}^n e^{x_i}) using a maximum-element trick to avoid arithmetic overflow.
static double	max(double[] x)
static void	sumFeatures(Context[] context, float[] values, double[] prior)
static double[]	toDoubleArray(List<Double> list) Convert a list of Double objects into an array of primitive doubles
static int[]	toIntArray(List<Integer> list) Convert a list of Integer objects into an array of primitive integers

Methods inherited from class java.lang.Object

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

Constructor Detail

ArrayMath

public ArrayMath()

Method Detail

innerProduct

public static double innerProduct(double[] vecA,
                                  double[] vecB)

l1norm

public static double l1norm(double[] v)

L1-norm

l2norm

public static double l2norm(double[] v)

L2-norm

invL2norm

public static double invL2norm(double[] v)

Inverse L2-norm

logSumOfExps

public static double logSumOfExps(double[] x)

Computes \log(\sum_{i=1}^n e^{x_i}) using a maximum-element trick to avoid arithmetic overflow.

Parameters:

x - input vector

Returns:

log-sum of exponentials of vector elements

max

public static double max(double[] x)

argmax

public static int argmax(double[] x)

Find index of maximum element in the vector x

Parameters:

x - input vector

Returns:

index of the maximum element. Index of the first maximum element is returned if multiple maximums are found.

sumFeatures

public static void sumFeatures(Context[] context,
                               float[] values,
                               double[] prior)

toDoubleArray

public static double[] toDoubleArray(List<Double> list)

Convert a list of Double objects into an array of primitive doubles

toIntArray

public static int[] toIntArray(List<Integer> list)

Convert a list of Integer objects into an array of primitive integers