org.apache.lucene.analysis.shingle
Class ShingleFilter

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

All Implemented Interfaces:

Closeable

public final class ShingleFilter
extends org.apache.lucene.analysis.TokenFilter

A ShingleFilter 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".

This filter handles position increments > 1 by inserting filler tokens (tokens with termtext "_"). It does not handle a position increment of 0.

Nested Class Summary

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 int	DEFAULT_MAX_SHINGLE_SIZE default maximum shingle size is 2.
static char[]	FILLER_TOKEN filler token for when positionIncrement is more than 1
static String	TOKEN_SEPARATOR The string to use when joining adjacent tokens to form a shingle

Fields inherited from class org.apache.lucene.analysis.TokenFilter

input

Constructor Summary

ShingleFilter(org.apache.lucene.analysis.TokenStream input)
Construct a ShingleFilter with default shingle size.

ShingleFilter(org.apache.lucene.analysis.TokenStream input, int maxShingleSize)
Constructs a ShingleFilter with the specified single size from the TokenStream input

ShingleFilter(org.apache.lucene.analysis.TokenStream input, String tokenType)
Construct a ShingleFilter with the specified token type for shingle tokens.

Method Summary

boolean	incrementToken()
void	reset()
void	setMaxShingleSize(int maxShingleSize) Set the max shingle size (default: 2)
void	setOutputUnigrams(boolean outputUnigrams) Shall the output stream contain the input tokens (unigrams) as well as shingles? (default: true.)
void	setTokenType(String tokenType) Set the type of the shingle tokens produced by this filter.

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

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

FILLER_TOKEN

public static final char[] FILLER_TOKEN

filler token for when positionIncrement is more than 1

DEFAULT_MAX_SHINGLE_SIZE

public static final int DEFAULT_MAX_SHINGLE_SIZE

default maximum shingle size is 2.

See Also:

Constant Field Values

TOKEN_SEPARATOR

public static final String TOKEN_SEPARATOR

The string to use when joining adjacent tokens to form a shingle

See Also:

Constant Field Values

Constructor Detail

ShingleFilter

public ShingleFilter(org.apache.lucene.analysis.TokenStream input,
                     int maxShingleSize)

Constructs a ShingleFilter with the specified single size from the TokenStream input

Parameters:

input - input stream

maxShingleSize - maximum shingle size produced by the filter.

ShingleFilter

public ShingleFilter(org.apache.lucene.analysis.TokenStream input)

Construct a ShingleFilter with default shingle size.

Parameters:

input - input stream

ShingleFilter

public ShingleFilter(org.apache.lucene.analysis.TokenStream input,
                     String tokenType)

Construct a ShingleFilter with the specified token type for shingle tokens.

Parameters:

input - input stream

tokenType - token type for shingle tokens

Method Detail

setTokenType

public void setTokenType(String tokenType)

Set the type of the shingle tokens produced by this filter. (default: "shingle")

Parameters:

tokenType - token tokenType

setOutputUnigrams

public void setOutputUnigrams(boolean outputUnigrams)

Shall the output stream contain the input tokens (unigrams) as well as shingles? (default: true.)

Parameters:

outputUnigrams - Whether or not the output stream shall contain the input tokens (unigrams)

setMaxShingleSize

public void setMaxShingleSize(int maxShingleSize)

Set the max shingle size (default: 2)

Parameters:

maxShingleSize - max size of output shingles

incrementToken

public final boolean incrementToken()
                             throws IOException

Specified by:

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

Throws:

IOException

reset

public void reset()
           throws IOException

Overrides:

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

Throws:

IOException