Package 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`, `AutoCloseable`, `Unwrappable<TokenStream>`

public final class ShingleFilter extends 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

`AttributeSource.State`

## Field Summary

Fields
Modifier and Type
Field
Description
`static final String`
`DEFAULT_FILLER_TOKEN`
filler token for when positionIncrement is more than 1
`static final int`
`DEFAULT_MAX_SHINGLE_SIZE`
default maximum shingle size is 2.
`static final int`
`DEFAULT_MIN_SHINGLE_SIZE`
default minimum shingle size is 2.
`static final String`
`DEFAULT_TOKEN_SEPARATOR`
The default string to use when joining adjacent tokens to form a shingle
`static final String`
`DEFAULT_TOKEN_TYPE`
default token type attribute value is "shingle"

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

`input`

### Fields inherited from class org.apache.lucene.analysis.TokenStream

`DEFAULT_TOKEN_ATTRIBUTE_FACTORY`

## Constructor Summary

Constructors
Constructor
Description
`ShingleFilter(TokenStream input)`
Construct a ShingleFilter with default shingle size: 2.
`ShingleFilter(TokenStream input, int maxShingleSize)`
Constructs a ShingleFilter with the specified shingle size from the `TokenStream` `input`
`ShingleFilter(TokenStream input, int minShingleSize, int maxShingleSize)`
Constructs a ShingleFilter with the specified shingle size from the `TokenStream` `input`
`ShingleFilter(TokenStream input, String tokenType)`
Construct a ShingleFilter with the specified token type for shingle tokens and the default shingle size: 2

## Method Summary

Modifier and Type
Method
Description
`void`
`end()`
`boolean`
`incrementToken()`
`void`
`reset()`
`void`
`setFillerToken(String fillerToken)`
Sets the string to insert for each position at which there is no token (i.e., when position increment is greater than one).
`void`
`setMaxShingleSize(int maxShingleSize)`
Set the max shingle size (default: 2)
`void`
`setMinShingleSize(int minShingleSize)`
Set the min shingle size (default: 2).
`void`
`setOutputUnigrams(boolean outputUnigrams)`
Shall the output stream contain the input tokens (unigrams) as well as shingles? (default: true.)
`void`
`setOutputUnigramsIfNoShingles(boolean outputUnigramsIfNoShingles)`
Shall we override the behavior of outputUnigrams==false for those times when no shingles are available (because there are fewer than minShingleSize tokens in the input stream)? (default: false.)
`void`
`setTokenSeparator(String tokenSeparator)`
Sets the string to use when joining adjacent tokens to form a shingle
`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, unwrap`

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

`addAttribute, addAttributeImpl, captureState, clearAttributes, cloneAttributes, copyTo, endAttributes, equals, getAttribute, getAttributeClassesIterator, getAttributeFactory, getAttributeImplsIterator, hasAttribute, hasAttributes, hashCode, reflectAsString, reflectWith, removeAllAttributes, restoreState, toString`

### Methods inherited from class java.lang.Object

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

## Field Details

### DEFAULT_FILLER_TOKEN

public static final String DEFAULT_FILLER_TOKEN
filler token for when positionIncrement is more than 1

See Also:
  - Constant Field Values

### DEFAULT_MAX_SHINGLE_SIZE

public static final int DEFAULT_MAX_SHINGLE_SIZE
default maximum shingle size is 2.

See Also:
  - Constant Field Values

### DEFAULT_MIN_SHINGLE_SIZE

public static final int DEFAULT_MIN_SHINGLE_SIZE
default minimum shingle size is 2.

See Also:
  - Constant Field Values

### DEFAULT_TOKEN_TYPE

public static final String DEFAULT_TOKEN_TYPE
default token type attribute value is "shingle"

See Also:
  - Constant Field Values

### DEFAULT_TOKEN_SEPARATOR

public static final String DEFAULT_TOKEN_SEPARATOR
The default string to use when joining adjacent tokens to form a shingle

See Also:
  - Constant Field Values

## Constructor Details

### ShingleFilter

public ShingleFilter(TokenStream input, int minShingleSize, int maxShingleSize)
Constructs a ShingleFilter with the specified shingle size from the `TokenStream` `input`

Parameters:
  `input` - input stream
  `minShingleSize` - minimum shingle size produced by the filter.
  `maxShingleSize` - maximum shingle size produced by the filter.

### ShingleFilter

public ShingleFilter(TokenStream input, int maxShingleSize)
Constructs a ShingleFilter with the specified shingle size from the `TokenStream` `input`

Parameters:
  `input` - input stream
  `maxShingleSize` - maximum shingle size produced by the filter.

### ShingleFilter

public ShingleFilter(TokenStream input)
Construct a ShingleFilter with default shingle size: 2.

Parameters:
  `input` - input stream

### ShingleFilter

public ShingleFilter(TokenStream input, String tokenType)
Construct a ShingleFilter with the specified token type for shingle tokens and the default shingle size: 2

Parameters:
  `input` - input stream
  `tokenType` - token type for shingle tokens

## Method Details

### 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)

### setOutputUnigramsIfNoShingles

public void setOutputUnigramsIfNoShingles(boolean outputUnigramsIfNoShingles)
Shall we override the behavior of outputUnigrams==false for those times when no shingles are available (because there are fewer than minShingleSize tokens in the input stream)? (default: false.)

Note that if outputUnigrams==true, then unigrams are always output, regardless of whether any shingles are available.

Parameters:
  `outputUnigramsIfNoShingles` - Whether or not to output a single unigram when no shingles are available.

### setMaxShingleSize

public void setMaxShingleSize(int maxShingleSize)
Set the max shingle size (default: 2)

Parameters:
  `maxShingleSize` - max size of output shingles

### setMinShingleSize

public void setMinShingleSize(int minShingleSize)
Set the min shingle size (default: 2).

This method requires that the passed in minShingleSize is not greater than maxShingleSize, so make sure that maxShingleSize is set before calling this method.

The unigram output option is independent of the min shingle size.

Parameters:
  `minShingleSize` - min size of output shingles

### setTokenSeparator

public void setTokenSeparator(String tokenSeparator)
Sets the string to use when joining adjacent tokens to form a shingle

Parameters:
  `tokenSeparator` - used to separate input stream tokens in output shingles

### setFillerToken

public void setFillerToken(String fillerToken)
Sets the string to insert for each position at which there is no token (i.e., when position increment is greater than one).

Parameters:
  `fillerToken` - string to insert at each position where there is no token

### incrementToken

public boolean incrementToken() throws IOException

Specified by:
  `incrementToken` in class `TokenStream`
Throws:
  `IOException`

### end

public void end() throws IOException

Overrides:
  `end` in class `TokenFilter`
Throws:
  `IOException`

### reset

public void reset() throws IOException

Overrides:
  `reset` in class `TokenFilter`
Throws:
  `IOException`