Module org.apache.lucene.core
Package org.apache.lucene.util

Class VectorUtil

java.lang.Object
org.apache.lucene.util.VectorUtil
public final class VectorUtil extends Object
Utilities for computations with numeric arrays

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    private
    VectorUtil()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    static void
    add(float[] u, float[] v)
    Adds the second argument to the first
    static float
    cosine(byte[] a, byte[] b)
    Returns the cosine similarity between the two vectors.
    static float
    cosine(float[] v1, float[] v2)
    Returns the cosine similarity between the two vectors.
    static float
    dotProduct(byte[] a, byte[] b)
    Dot product computed over signed bytes.
    static float
    dotProduct(float[] a, float[] b)
    Returns the vector dot product of the two vectors.
    static float
    dotProductScore(byte[] a, byte[] b)
    Dot product score computed over signed bytes, scaled to be in [0, 1].
    static float[]
    l2normalize(float[] v)
    Modifies the argument to be unit length, dividing by its l2-norm.
    static float[]
    l2normalize(float[] v, boolean throwOnZero)
    Modifies the argument to be unit length, dividing by its l2-norm.
    static float
    squareDistance(byte[] a, byte[] b)
    Returns the sum of squared differences of the two vectors.
    static float
    squareDistance(float[] v1, float[] v2)
    Returns the sum of squared differences of the two vectors.
    private static float
    squareDistanceUnrolled(float[] v1, float[] v2, int index)
     
    static BytesRef
    toBytesRef(float[] vector)
    Convert a floating point vector to an array of bytes using casting; the vector values should be in [-128,127]

    Methods inherited from class java.lang.Object

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

  • Constructor Details

    • VectorUtil

      private VectorUtil()

  • Method Details

    • dotProduct

      public static float dotProduct(float[] a, float[] b)
      Returns the vector dot product of the two vectors.
      Throws:
      IllegalArgumentException - if the vectors' dimensions differ.

    • cosine

      public static float cosine(float[] v1, float[] v2)
      Returns the cosine similarity between the two vectors.
      Throws:
      IllegalArgumentException - if the vectors' dimensions differ.

    • cosine

      public static float cosine(byte[] a, byte[] b)
      Returns the cosine similarity between the two vectors.

    • squareDistance

      public static float squareDistance(float[] v1, float[] v2)
      Returns the sum of squared differences of the two vectors.
      Throws:
      IllegalArgumentException - if the vectors' dimensions differ.

    • squareDistanceUnrolled

      private static float squareDistanceUnrolled(float[] v1, float[] v2, int index)

    • squareDistance

      public static float squareDistance(byte[] a, byte[] b)
      Returns the sum of squared differences of the two vectors.

    • l2normalize

      public static float[] l2normalize(float[] v)
      Modifies the argument to be unit length, dividing by its l2-norm. IllegalArgumentException is thrown for zero vectors.
      Returns:
      the input array after normalization

    • l2normalize

      public static float[] l2normalize(float[] v, boolean throwOnZero)
      Modifies the argument to be unit length, dividing by its l2-norm.
      Parameters:
      v - the vector to normalize
      throwOnZero - whether to throw an exception when v has all zeros
      Returns:
      the input array after normalization
      Throws:
      IllegalArgumentException - when the vector is all zero and throwOnZero is true

    • add

      public static void add(float[] u, float[] v)
      Adds the second argument to the first
      Parameters:
      u - the destination
      v - the vector to add to the destination

    • dotProduct

      public static float dotProduct(byte[] a, byte[] b)
      Dot product computed over signed bytes.
      Parameters:
      a - bytes containing a vector
      b - bytes containing another vector, of the same dimension
      Returns:
      the value of the dot product of the two vectors

    • dotProductScore

      public static float dotProductScore(byte[] a, byte[] b)
      Dot product score computed over signed bytes, scaled to be in [0, 1].
      Parameters:
      a - bytes containing a vector
      b - bytes containing another vector, of the same dimension
      Returns:
      the value of the similarity function applied to the two vectors

    • toBytesRef

      public static BytesRef toBytesRef(float[] vector)
      Convert a floating point vector to an array of bytes using casting; the vector values should be in [-128,127]
      Parameters:
      vector - a vector
      Returns:
      a new BytesRef containing the vector's values cast to byte.