Package org.apache.lucene.util
Class VectorUtil
- java.lang.Object
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- org.apache.lucene.util.VectorUtil
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public final class VectorUtil extends Object
Utilities for computations with numeric arrays
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static void
add(float[] u, float[] v)
Adds the second argument to the firststatic 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.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]
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Method Detail
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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.
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cosine
public static float cosine(float[] v1, float[] v2)
Returns the cosine similarity between the two vectors.- Throws:
IllegalArgumentException
- if the vectors' dimensions differ.
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cosine
public static float cosine(byte[] a, byte[] b)
Returns the cosine similarity between the two vectors.
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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.
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squareDistance
public static float squareDistance(byte[] a, byte[] b)
Returns the sum of squared differences of the two vectors.
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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
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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 normalizethrowOnZero
- whether to throw an exception whenv
has all zeros- Returns:
- the input array after normalization
- Throws:
IllegalArgumentException
- when the vector is all zero and throwOnZero is true
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add
public static void add(float[] u, float[] v)
Adds the second argument to the first- Parameters:
u
- the destinationv
- the vector to add to the destination
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dotProduct
public static float dotProduct(byte[] a, byte[] b)
Dot product computed over signed bytes.- Parameters:
a
- bytes containing a vectorb
- bytes containing another vector, of the same dimension- Returns:
- the value of the dot product of the two vectors
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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 vectorb
- bytes containing another vector, of the same dimension- Returns:
- the value of the similarity function applied to the two vectors
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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.
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