Package opennlp.tools.ml

Class ArrayMath

  • Direct Known Subclasses:
    ArrayMath
    public class ArrayMath
extends Object
    Utility class for simple vector arithmetic.

    • Constructor Summary

      Constructors 
      Constructor Description
      ArrayMath()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static int argmax​(double[] x)
      Finds the index of the maximum element in a vector x
      static double innerProduct​(double[] vecA, double[] vecB)  
      static double invL2norm​(double[] v)
      Computes the Inverse L2-norm for a vector v.
      static double l1norm​(double[] v)
      Computes the L1-norm for a vector v.
      static double l2norm​(double[] v)
      Computes the L2-norm for a vector v.
      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)
      Finds the maximum element in a vector 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.

    • Constructor Detail

      • ArrayMath

        public ArrayMath()

    • Method Detail

      • innerProduct

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

      • l1norm

        public static double l1norm​(double[] v)
        Computes the L1-norm for a vector v.
        Parameters:
        v - The vector of double values.
        Returns:
        The computed L1-norm.

      • l2norm

        public static double l2norm​(double[] v)
        Computes the L2-norm for a vector v.
        Parameters:
        v - The vector of double values.
        Returns:
        The computed L2-norm.

      • invL2norm

        public static double invL2norm​(double[] v)
        Computes the Inverse L2-norm for a vector v.
        Parameters:
        v - The vector of double values.
        Returns:
        The computed 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 - The vector of double values.
        Returns:
        The log-sum of exponentials of vector elements.

      • max

        public static double max​(double[] x)
        Finds the maximum element in a vector x.
        Parameters:
        x - The vector of double values.
        Returns:
        The maximum element in x.

      • argmax

        public static int argmax​(double[] x)
        Finds the index of the maximum element in a vector x
        Parameters:
        x - The vector of double values.
        Returns:
        The 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.
        Parameters:
        list - The input vector of values.
        Returns:
        The double[].

      • toIntArray

        public static int[] toIntArray​(List<Integer> list)
        Convert a list of Integer objects into an array of primitive integers.
        Parameters:
        list - The input vector of values.
        Returns:
        The int[].