org.apache.lucene.analysis.shingle
Class ShingleMatrixFilter

java.lang.Object
  org.apache.lucene.util.AttributeSource
      org.apache.lucene.analysis.TokenStream
          org.apache.lucene.analysis.shingle.ShingleMatrixFilter

All Implemented Interfaces:

Closeable

public final class ShingleMatrixFilter
extends org.apache.lucene.analysis.TokenStream

A ShingleMatrixFilter constructs shingles (token n-grams) from a token stream. In other words, it creates combinations of tokens as a single token.

For example, the sentence "please divide this sentence into shingles" might be tokenized into shingles "please divide", "divide this", "this sentence", "sentence into", and "into shingles".

Using a shingle filter at index and query time can in some instances be used to replace phrase queries, especially them with 0 slop.

Without a spacer character it can be used to handle composition and decomposition of words such as searching for "multi dimensional" instead of "multidimensional". It is a rather common human problem at query time in several languages, notably the northern Germanic branch.

Shingles are amongst many things also known to solve problems in spell checking, language detection and document clustering.

This filter is backed by a three dimensional column oriented matrix used to create permutations of the second dimension, the rows, and leaves the third, the z-axis, for for multi token synonyms.

In order to use this filter you need to define a way of positioning the input stream tokens in the matrix. This is done using a ShingleMatrixFilter.TokenSettingsCodec. There are three simple implementations for demonstrational purposes, see ShingleMatrixFilter.OneDimensionalNonWeightedTokenSettingsCodec, ShingleMatrixFilter.TwoDimensionalNonWeightedSynonymTokenSettingsCodec and ShingleMatrixFilter.SimpleThreeDimensionalTokenSettingsCodec.

Consider this token matrix:

  Token[column][row][z-axis]{
    {{hello}, {greetings, and, salutations}},
    {{world}, {earth}, {tellus}}
  };
 

It would produce the following 2-3 gram sized shingles:

 "hello_world"
 "greetings_and"
 "greetings_and_salutations"
 "and_salutations"
 "and_salutations_world"
 "salutations_world"
 "hello_earth"
 "and_salutations_earth"
 "salutations_earth"
 "hello_tellus"
 "and_salutations_tellus"
 "salutations_tellus"
  

This implementation can be rather heap demanding if (maximum shingle size - minimum shingle size) is a great number and the stream contains many columns, or if each column contains a great number of rows.

The problem is that in order avoid producing duplicates the filter needs to keep track of any shingle already produced and returned to the consumer. There is a bit of resource management to handle this but it would of course be much better if the filter was written so it never created the same shingle more than once in the first place.

The filter also has basic support for calculating weights for the shingles based on the weights of the tokens from the input stream, output shingle size, etc. See calculateShingleWeight(org.apache.lucene.analysis.Token, java.util.List, int, java.util.List, java.util.List).

NOTE: This filter might not behave correctly if used with custom Attributes, i.e. Attributes other than the ones located in org.apache.lucene.analysis.tokenattributes.

Nested Class Summary

static class	ShingleMatrixFilter.Matrix A column focused matrix in three dimensions:
static class	ShingleMatrixFilter.OneDimensionalNonWeightedTokenSettingsCodec Using this codec makes a ShingleMatrixFilter act like ShingleFilter.
static class	ShingleMatrixFilter.SimpleThreeDimensionalTokenSettingsCodec A full featured codec not to be used for something serious.
static class	ShingleMatrixFilter.TokenPositioner Used to describe how a Token is to be inserted to a ShingleMatrixFilter.Matrix.
static class	ShingleMatrixFilter.TokenSettingsCodec Strategy used to code and decode meta data of the tokens from the input stream regarding how to position the tokens in the matrix, set and retreive weight, et c.
static class	ShingleMatrixFilter.TwoDimensionalNonWeightedSynonymTokenSettingsCodec A codec that creates a two dimensional matrix by treating tokens from the input stream with 0 position increment as new rows to the current column.

Nested classes/interfaces inherited from class org.apache.lucene.util.AttributeSource

org.apache.lucene.util.AttributeSource.AttributeFactory, org.apache.lucene.util.AttributeSource.State

Field Summary

static ShingleMatrixFilter.TokenSettingsCodec	defaultSettingsCodec
static Character	defaultSpacerCharacter
static boolean	ignoringSinglePrefixOrSuffixShingleByDefault

Constructor Summary

ShingleMatrixFilter(ShingleMatrixFilter.Matrix matrix, int minimumShingleSize, int maximumShingleSize, Character spacerCharacter, boolean ignoringSinglePrefixOrSuffixShingle, ShingleMatrixFilter.TokenSettingsCodec settingsCodec)
Creates a shingle filter based on a user defined matrix.

ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input, int minimumShingleSize, int maximumShingleSize)
Creates a shingle filter using default settings.

ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input, int minimumShingleSize, int maximumShingleSize, Character spacerCharacter)
Creates a shingle filter using default settings.

ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input, int minimumShingleSize, int maximumShingleSize, Character spacerCharacter, boolean ignoringSinglePrefixOrSuffixShingle)
Creates a shingle filter using the default ShingleMatrixFilter.TokenSettingsCodec.

ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input, int minimumShingleSize, int maximumShingleSize, Character spacerCharacter, boolean ignoringSinglePrefixOrSuffixShingle, ShingleMatrixFilter.TokenSettingsCodec settingsCodec)
Creates a shingle filter with ad hoc parameter settings.

Method Summary

float	calculateShingleWeight(org.apache.lucene.analysis.Token shingleToken, List<org.apache.lucene.analysis.Token> shingle, int currentPermutationStartOffset, List<ShingleMatrixFilter.Matrix.Column.Row> currentPermutationRows, List<org.apache.lucene.analysis.Token> currentPermuationTokens) Evaluates the new shingle token weight.
ShingleMatrixFilter.Matrix	getMatrix()
int	getMaximumShingleSize()
int	getMinimumShingleSize()
Character	getSpacerCharacter()
boolean	incrementToken()
boolean	isIgnoringSinglePrefixOrSuffixShingle()
void	reset()
void	setIgnoringSinglePrefixOrSuffixShingle(boolean ignoringSinglePrefixOrSuffixShingle)
void	setMatrix(ShingleMatrixFilter.Matrix matrix)
void	setMaximumShingleSize(int maximumShingleSize)
void	setMinimumShingleSize(int minimumShingleSize)
void	setSpacerCharacter(Character spacerCharacter)
void	updateToken(org.apache.lucene.analysis.Token token, List<org.apache.lucene.analysis.Token> shingle, int currentPermutationStartOffset, List<ShingleMatrixFilter.Matrix.Column.Row> currentPermutationRows, List<org.apache.lucene.analysis.Token> currentPermuationTokens) Final touch of a shingle token before it is passed on to the consumer from method incrementToken().

Methods inherited from class org.apache.lucene.analysis.TokenStream

close, end

Methods inherited from class org.apache.lucene.util.AttributeSource

addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, restoreState, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

defaultSpacerCharacter

public static Character defaultSpacerCharacter

defaultSettingsCodec

public static ShingleMatrixFilter.TokenSettingsCodec defaultSettingsCodec

ignoringSinglePrefixOrSuffixShingleByDefault

public static boolean ignoringSinglePrefixOrSuffixShingleByDefault

Constructor Detail

ShingleMatrixFilter

public ShingleMatrixFilter(ShingleMatrixFilter.Matrix matrix,
                           int minimumShingleSize,
                           int maximumShingleSize,
                           Character spacerCharacter,
                           boolean ignoringSinglePrefixOrSuffixShingle,
                           ShingleMatrixFilter.TokenSettingsCodec settingsCodec)

Creates a shingle filter based on a user defined matrix. The filter /will/ delete columns from the input matrix! You will not be able to reset the filter if you used this constructor. todo: don't touch the matrix! use a boolean, set the input stream to null or something, and keep track of where in the matrix we are at.

Parameters:

matrix - the input based for creating shingles. Does not need to contain any information until incrementToken() is called the first time.

minimumShingleSize - minimum number of tokens in any shingle.

maximumShingleSize - maximum number of tokens in any shingle.

spacerCharacter - character to use between texts of the token parts in a shingle. null for none.

ignoringSinglePrefixOrSuffixShingle - if true, shingles that only contains permutation of the first of the last column will not be produced as shingles. Useful when adding boundary marker tokens such as '^' and '$'.

settingsCodec - codec used to read input token weight and matrix positioning.

ShingleMatrixFilter

public ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input,
                           int minimumShingleSize,
                           int maximumShingleSize)

Creates a shingle filter using default settings.

Parameters:

input - stream from which to construct the matrix

minimumShingleSize - minimum number of tokens in any shingle.

maximumShingleSize - maximum number of tokens in any shingle.

See Also:

defaultSpacerCharacter, ignoringSinglePrefixOrSuffixShingleByDefault, defaultSettingsCodec

ShingleMatrixFilter

public ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input,
                           int minimumShingleSize,
                           int maximumShingleSize,
                           Character spacerCharacter)

Creates a shingle filter using default settings.

Parameters:

input - stream from which to construct the matrix

minimumShingleSize - minimum number of tokens in any shingle.

maximumShingleSize - maximum number of tokens in any shingle.

spacerCharacter - character to use between texts of the token parts in a shingle. null for none.

See Also:

ignoringSinglePrefixOrSuffixShingleByDefault, defaultSettingsCodec

ShingleMatrixFilter

public ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input,
                           int minimumShingleSize,
                           int maximumShingleSize,
                           Character spacerCharacter,
                           boolean ignoringSinglePrefixOrSuffixShingle)

Creates a shingle filter using the default ShingleMatrixFilter.TokenSettingsCodec.

Parameters:

input - stream from which to construct the matrix

minimumShingleSize - minimum number of tokens in any shingle.

maximumShingleSize - maximum number of tokens in any shingle.

spacerCharacter - character to use between texts of the token parts in a shingle. null for none.

ignoringSinglePrefixOrSuffixShingle - if true, shingles that only contains permutation of the first of the last column will not be produced as shingles. Useful when adding boundary marker tokens such as '^' and '$'.

See Also:

defaultSettingsCodec

ShingleMatrixFilter

public ShingleMatrixFilter(org.apache.lucene.analysis.TokenStream input,
                           int minimumShingleSize,
                           int maximumShingleSize,
                           Character spacerCharacter,
                           boolean ignoringSinglePrefixOrSuffixShingle,
                           ShingleMatrixFilter.TokenSettingsCodec settingsCodec)

Creates a shingle filter with ad hoc parameter settings.

Parameters:

input - stream from which to construct the matrix

minimumShingleSize - minimum number of tokens in any shingle.

maximumShingleSize - maximum number of tokens in any shingle.

spacerCharacter - character to use between texts of the token parts in a shingle. null for none.

ignoringSinglePrefixOrSuffixShingle - if true, shingles that only contains permutation of the first of the last column will not be produced as shingles. Useful when adding boundary marker tokens such as '^' and '$'.

settingsCodec - codec used to read input token weight and matrix positioning.

Method Detail

reset

public void reset()
           throws IOException

Overrides:

reset in class org.apache.lucene.analysis.TokenStream

Throws:

IOException

incrementToken

public final boolean incrementToken()
                             throws IOException

Specified by:

incrementToken in class org.apache.lucene.analysis.TokenStream

Throws:

IOException

updateToken

public void updateToken(org.apache.lucene.analysis.Token token,
                        List<org.apache.lucene.analysis.Token> shingle,
                        int currentPermutationStartOffset,
                        List<ShingleMatrixFilter.Matrix.Column.Row> currentPermutationRows,
                        List<org.apache.lucene.analysis.Token> currentPermuationTokens)

Final touch of a shingle token before it is passed on to the consumer from method incrementToken(). Calculates and sets type, flags, position increment, start/end offsets and weight.

Parameters:

token - Shingle token

shingle - Tokens used to produce the shingle token.

currentPermutationStartOffset - Start offset in parameter currentPermutationTokens

currentPermutationRows - index to Matrix.Column.Row from the position of tokens in parameter currentPermutationTokens

currentPermuationTokens - tokens of the current permutation of rows in the matrix.

calculateShingleWeight

public float calculateShingleWeight(org.apache.lucene.analysis.Token shingleToken,
                                    List<org.apache.lucene.analysis.Token> shingle,
                                    int currentPermutationStartOffset,
                                    List<ShingleMatrixFilter.Matrix.Column.Row> currentPermutationRows,
                                    List<org.apache.lucene.analysis.Token> currentPermuationTokens)

Evaluates the new shingle token weight. for (shingle part token in shingle) weight += shingle part token weight * (1 / sqrt(all shingle part token weights summed)) This algorithm gives a slightly greater score for longer shingles and is rather penalising to great shingle token part weights.

Parameters:

shingleToken - token returned to consumer

shingle - tokens the tokens used to produce the shingle token.

currentPermutationStartOffset - start offset in parameter currentPermutationRows and currentPermutationTokens.

currentPermutationRows - an index to what matrix row a token in parameter currentPermutationTokens exist.

currentPermuationTokens - all tokens in the current row permutation of the matrix. A sub list (parameter offset, parameter shingle.size) equals parameter shingle.

Returns:

weight to be set for parameter shingleToken

getMinimumShingleSize

public int getMinimumShingleSize()

setMinimumShingleSize

public void setMinimumShingleSize(int minimumShingleSize)

getMaximumShingleSize

public int getMaximumShingleSize()

setMaximumShingleSize

public void setMaximumShingleSize(int maximumShingleSize)

getMatrix

public ShingleMatrixFilter.Matrix getMatrix()

setMatrix

public void setMatrix(ShingleMatrixFilter.Matrix matrix)

getSpacerCharacter

public Character getSpacerCharacter()

setSpacerCharacter

public void setSpacerCharacter(Character spacerCharacter)

isIgnoringSinglePrefixOrSuffixShingle

public boolean isIgnoringSinglePrefixOrSuffixShingle()

setIgnoringSinglePrefixOrSuffixShingle

public void setIgnoringSinglePrefixOrSuffixShingle(boolean ignoringSinglePrefixOrSuffixShingle)