Module org.apache.lucene.suggest

Package org.apache.lucene.search.spell

Class WordBreakSpellChecker

java.lang.Object

org.apache.lucene.search.spell.WordBreakSpellChecker

public class WordBreakSpellChecker
extends Object

A spell checker whose sole function is to offer suggestions by combining multiple terms into one word and/or breaking terms into multiple words.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static enum	WordBreakSpellChecker.BreakSuggestionSortMethod	Determines the order to list word break suggestions
private static class	WordBreakSpellChecker.CombinationsThenFreqComparator
private static class	WordBreakSpellChecker.CombineSuggestionWrapper
private static class	WordBreakSpellChecker.LengthThenMaxFreqComparator
private static class	WordBreakSpellChecker.LengthThenSumFreqComparator
private static class	WordBreakSpellChecker.SuggestWordArrayWrapper

Field Summary

Fields

Modifier and Type	Field	Description
private int	maxChanges
private int	maxCombineWordLength
private int	maxEvaluations
private int	minBreakWordLength
private int	minSuggestionFrequency
static final Term	SEPARATOR_TERM	Term that can be used to prohibit adjacent terms from being combined

Constructor Summary

Constructors

Constructor	Description
WordBreakSpellChecker()	Creates a new spellchecker with default configuration values

Method Summary

Modifier and Type	Method	Description
private int	generateBreakUpSuggestions(Term term, IndexReader ir, int numberBreaks, int maxSuggestions, int useMinSuggestionFrequency, SuggestWord[] prefix, Queue<WordBreakSpellChecker.SuggestWordArrayWrapper> suggestions, int totalEvaluations, WordBreakSpellChecker.BreakSuggestionSortMethod sortMethod)
private SuggestWord	generateSuggestWord(IndexReader ir, String fieldname, String text)
int	getMaxChanges()	Returns the maximum number of changes to perform on the input
int	getMaxCombineWordLength()	Returns the maximum length of a combined suggestion
int	getMaxEvaluations()	Returns the maximum number of word combinations to evaluate.
int	getMinBreakWordLength()	Returns the minimum size of a broken word
int	getMinSuggestionFrequency()	Returns the minimum frequency a term must have to be part of a suggestion.
private SuggestWord[]	newPrefix(SuggestWord[] oldPrefix, SuggestWord append)
private SuggestWord[]	newSuggestion(SuggestWord[] prefix, SuggestWord append1, SuggestWord append2)
void	setMaxChanges(int maxChanges)	The maximum numbers of changes (word breaks or combinations) to make on the original term(s).
void	setMaxCombineWordLength(int maxCombineWordLength)	The maximum length of a suggestion made by combining 1 or more original terms.
void	setMaxEvaluations(int maxEvaluations)	The maximum number of word combinations to evaluate.
void	setMinBreakWordLength(int minBreakWordLength)	The minimum length to break words down to.
void	setMinSuggestionFrequency(int minSuggestionFrequency)	The minimum frequency a term must have to be included as part of a suggestion.
SuggestWord[][]	suggestWordBreaks(Term term, int maxSuggestions, IndexReader ir, SuggestMode suggestMode, WordBreakSpellChecker.BreakSuggestionSortMethod sortMethod)	Generate suggestions by breaking the passed-in term into multiple words.
CombineSuggestion[]	suggestWordCombinations(Term[] terms, int maxSuggestions, IndexReader ir, SuggestMode suggestMode)	Generate suggestions by combining one or more of the passed-in terms into single words.

Methods inherited from class java.lang.Object

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

Field Details

minSuggestionFrequency

private int minSuggestionFrequency

minBreakWordLength

private int minBreakWordLength

maxCombineWordLength

private int maxCombineWordLength

maxChanges

private int maxChanges

maxEvaluations

private int maxEvaluations

SEPARATOR_TERM

public static final Term SEPARATOR_TERM

Term that can be used to prohibit adjacent terms from being combined

Constructor Details

WordBreakSpellChecker

public WordBreakSpellChecker()

Creates a new spellchecker with default configuration values

See Also:

• setMaxChanges(int)
• setMaxCombineWordLength(int)
• setMaxEvaluations(int)
• setMinBreakWordLength(int)
• setMinSuggestionFrequency(int)

Method Details

suggestWordBreaks

public SuggestWord[][] suggestWordBreaks(Term term,
 int maxSuggestions,
 IndexReader ir,
 SuggestMode suggestMode,
 WordBreakSpellChecker.BreakSuggestionSortMethod sortMethod)
                                  throws IOException

Generate suggestions by breaking the passed-in term into multiple words. The scores returned are equal to the number of word breaks needed so a lower score is generally preferred over a higher score.

Parameters:

suggestMode - - default = SuggestMode.SUGGEST_WHEN_NOT_IN_INDEX

sortMethod - - default = WordBreakSpellChecker.BreakSuggestionSortMethod.NUM_CHANGES_THEN_MAX_FREQUENCY

Returns:

one or more arrays of words formed by breaking up the original term

Throws:

IOException - If there is a low-level I/O error.

suggestWordCombinations

public CombineSuggestion[] suggestWordCombinations(Term[] terms,
 int maxSuggestions,
 IndexReader ir,
 SuggestMode suggestMode)
                                            throws IOException

Generate suggestions by combining one or more of the passed-in terms into single words. The returned CombineSuggestion contains both a SuggestWord and also an array detailing which passed-in terms were involved in creating this combination. The scores returned are equal to the number of word combinations needed, also one less than the length of the array CombineSuggestion.originalTermIndexes. Generally, a suggestion with a lower score is preferred over a higher score.

To prevent two adjacent terms from being combined (for instance, if one is mandatory and the other is prohibited), separate the two terms with SEPARATOR_TERM

When suggestMode equals SuggestMode.SUGGEST_WHEN_NOT_IN_INDEX, each suggestion will include at least one term not in the index.

When suggestMode equals SuggestMode.SUGGEST_MORE_POPULAR, each suggestion will have the same, or better frequency than the most-popular included term.

Returns:

an array of words generated by combining original terms

Throws:

IOException - If there is a low-level I/O error.

generateBreakUpSuggestions

private int generateBreakUpSuggestions(Term term,
 IndexReader ir,
 int numberBreaks,
 int maxSuggestions,
 int useMinSuggestionFrequency,
 SuggestWord[] prefix,
 Queue<WordBreakSpellChecker.SuggestWordArrayWrapper> suggestions,
 int totalEvaluations,
 WordBreakSpellChecker.BreakSuggestionSortMethod sortMethod)
                                throws IOException

Throws:

IOException

newPrefix

private SuggestWord[] newPrefix(SuggestWord[] oldPrefix,
 SuggestWord append)

newSuggestion

private SuggestWord[] newSuggestion(SuggestWord[] prefix,
 SuggestWord append1,
 SuggestWord append2)

generateSuggestWord

private SuggestWord generateSuggestWord(IndexReader ir,
 String fieldname,
 String text)
                                 throws IOException

Throws:

IOException

getMinSuggestionFrequency

public int getMinSuggestionFrequency()

Returns the minimum frequency a term must have to be part of a suggestion.

See Also:

• setMinSuggestionFrequency(int)

getMaxCombineWordLength

public int getMaxCombineWordLength()

Returns the maximum length of a combined suggestion

See Also:

• setMaxCombineWordLength(int)

getMinBreakWordLength

public int getMinBreakWordLength()

Returns the minimum size of a broken word

See Also:

• setMinBreakWordLength(int)

getMaxChanges

public int getMaxChanges()

Returns the maximum number of changes to perform on the input

See Also:

• setMaxChanges(int)

getMaxEvaluations

public int getMaxEvaluations()

Returns the maximum number of word combinations to evaluate.

See Also:

• setMaxEvaluations(int)

setMinSuggestionFrequency

public void setMinSuggestionFrequency(int minSuggestionFrequency)

The minimum frequency a term must have to be included as part of a suggestion. Default=1 Not applicable when used with SuggestMode.SUGGEST_MORE_POPULAR

See Also:

• getMinSuggestionFrequency()

setMaxCombineWordLength

public void setMaxCombineWordLength(int maxCombineWordLength)

The maximum length of a suggestion made by combining 1 or more original terms. Default=20

See Also:

• getMaxCombineWordLength()

setMinBreakWordLength

public void setMinBreakWordLength(int minBreakWordLength)

The minimum length to break words down to. Default=1

See Also:

• getMinBreakWordLength()

setMaxChanges

public void setMaxChanges(int maxChanges)

The maximum numbers of changes (word breaks or combinations) to make on the original term(s). Default=1

See Also:

• getMaxChanges()

setMaxEvaluations

public void setMaxEvaluations(int maxEvaluations)

The maximum number of word combinations to evaluate. Default=1000. A higher value might improve result quality. A lower value might improve performance.

See Also:

• getMaxEvaluations()