Class SpellChecker
- java.lang.Object
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- org.apache.lucene.search.spell.SpellChecker
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- All Implemented Interfaces:
Closeable,AutoCloseable
public class SpellChecker extends Object implements Closeable
Spell Checker class (Main class).
(initially inspired by the David Spencer code).Example Usage:
SpellChecker spellchecker = new SpellChecker(spellIndexDirectory); // To index a field of a user index: spellchecker.indexDictionary(new LuceneDictionary(my_lucene_reader, a_field)); // To index a file containing words: spellchecker.indexDictionary(new PlainTextDictionary(new File("myfile.txt"))); String[] suggestions = spellchecker.suggestSimilar("misspelt", 5);
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Field Summary
Fields Modifier and Type Field Description static floatDEFAULT_ACCURACYThe default minimum score to use, if not specified by callingsetAccuracy(float).static StringF_WORDField name for each word in the ngram index.
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Constructor Summary
Constructors Constructor Description SpellChecker(Directory spellIndex)Use the given directory as a spell checker index with aLevenshteinDistanceas the defaultStringDistance.SpellChecker(Directory spellIndex, StringDistance sd)Use the given directory as a spell checker index.SpellChecker(Directory spellIndex, StringDistance sd, Comparator<SuggestWord> comparator)Use the given directory as a spell checker index with the givenStringDistancemeasure and the givenComparatorfor sorting the results.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voidclearIndex()Removes all terms from the spell check index.voidclose()Close the IndexSearcher used by this SpellCheckerbooleanexist(String word)Check whether the word exists in the index.floatgetAccuracy()The accuracy (minimum score) to be used, unless overridden insuggestSimilar(String, int, IndexReader, String, SuggestMode, float), to decide whether a suggestion is included or not.Comparator<SuggestWord>getComparator()Gets the comparator in use for ranking suggestions.StringDistancegetStringDistance()Returns theStringDistanceinstance used by thisSpellCheckerinstance.voidindexDictionary(Dictionary dict, IndexWriterConfig config, boolean fullMerge)Indexes the data from the givenDictionary.voidsetAccuracy(float acc)Sets the accuracy 0 < minScore < 1; defaultDEFAULT_ACCURACYvoidsetComparator(Comparator<SuggestWord> comparator)Sets theComparatorfor theSuggestWordQueue.voidsetSpellIndex(Directory spellIndexDir)Use a different index as the spell checker index or re-open the existing index ifspellIndexis the same value as given in the constructor.voidsetStringDistance(StringDistance sd)Sets theStringDistanceimplementation for thisSpellCheckerinstance.String[]suggestSimilar(String word, int numSug)Suggest similar words.String[]suggestSimilar(String word, int numSug, float accuracy)Suggest similar words.String[]suggestSimilar(String word, int numSug, IndexReader ir, String field, SuggestMode suggestMode)String[]suggestSimilar(String word, int numSug, IndexReader ir, String field, SuggestMode suggestMode, float accuracy)Suggest similar words (optionally restricted to a field of an index).
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Field Detail
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DEFAULT_ACCURACY
public static final float DEFAULT_ACCURACY
The default minimum score to use, if not specified by callingsetAccuracy(float).- See Also:
- Constant Field Values
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F_WORD
public static final String F_WORD
Field name for each word in the ngram index.- See Also:
- Constant Field Values
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Constructor Detail
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SpellChecker
public SpellChecker(Directory spellIndex, StringDistance sd) throws IOException
Use the given directory as a spell checker index. The directory is created if it doesn't exist yet.- Parameters:
spellIndex- the spell index directorysd- theStringDistancemeasurement to use- Throws:
IOException- if Spellchecker can not open the directory
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SpellChecker
public SpellChecker(Directory spellIndex) throws IOException
Use the given directory as a spell checker index with aLevenshteinDistanceas the defaultStringDistance. The directory is created if it doesn't exist yet.- Parameters:
spellIndex- the spell index directory- Throws:
IOException- if spellchecker can not open the directory
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SpellChecker
public SpellChecker(Directory spellIndex, StringDistance sd, Comparator<SuggestWord> comparator) throws IOException
Use the given directory as a spell checker index with the givenStringDistancemeasure and the givenComparatorfor sorting the results.- Parameters:
spellIndex- The spelling indexsd- The distancecomparator- The comparator- Throws:
IOException- if there is a problem opening the index
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Method Detail
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setSpellIndex
public void setSpellIndex(Directory spellIndexDir) throws IOException
Use a different index as the spell checker index or re-open the existing index ifspellIndexis the same value as given in the constructor.- Parameters:
spellIndexDir- the spell directory to use- Throws:
AlreadyClosedException- if the Spellchecker is already closedIOException- if spellchecker can not open the directory
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setComparator
public void setComparator(Comparator<SuggestWord> comparator)
Sets theComparatorfor theSuggestWordQueue.- Parameters:
comparator- the comparator
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getComparator
public Comparator<SuggestWord> getComparator()
Gets the comparator in use for ranking suggestions.- See Also:
setComparator(Comparator)
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setStringDistance
public void setStringDistance(StringDistance sd)
Sets theStringDistanceimplementation for thisSpellCheckerinstance.- Parameters:
sd- theStringDistanceimplementation for thisSpellCheckerinstance
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getStringDistance
public StringDistance getStringDistance()
Returns theStringDistanceinstance used by thisSpellCheckerinstance.- Returns:
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StringDistanceinstance used by thisSpellCheckerinstance.
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setAccuracy
public void setAccuracy(float acc)
Sets the accuracy 0 < minScore < 1; defaultDEFAULT_ACCURACY- Parameters:
acc- The new accuracy
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getAccuracy
public float getAccuracy()
The accuracy (minimum score) to be used, unless overridden insuggestSimilar(String, int, IndexReader, String, SuggestMode, float), to decide whether a suggestion is included or not.- Returns:
- The current accuracy setting
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suggestSimilar
public String[] suggestSimilar(String word, int numSug) throws IOException
Suggest similar words.As the Lucene similarity that is used to fetch the most relevant n-grammed terms is not the same as the edit distance strategy used to calculate the best matching spell-checked word from the hits that Lucene found, one usually has to retrieve a couple of numSug's in order to get the true best match.
I.e. if numSug == 1, don't count on that suggestion being the best one. Thus, you should set this value to at least 5 for a good suggestion.
- Parameters:
word- the word you want a spell check done onnumSug- the number of suggested words- Returns:
- String[]
- Throws:
IOException- if the underlying index throws anIOExceptionAlreadyClosedException- if the Spellchecker is already closed- See Also:
suggestSimilar(String, int, IndexReader, String, SuggestMode, float)
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suggestSimilar
public String[] suggestSimilar(String word, int numSug, float accuracy) throws IOException
Suggest similar words.As the Lucene similarity that is used to fetch the most relevant n-grammed terms is not the same as the edit distance strategy used to calculate the best matching spell-checked word from the hits that Lucene found, one usually has to retrieve a couple of numSug's in order to get the true best match.
I.e. if numSug == 1, don't count on that suggestion being the best one. Thus, you should set this value to at least 5 for a good suggestion.
- Parameters:
word- the word you want a spell check done onnumSug- the number of suggested wordsaccuracy- The minimum score a suggestion must have in order to qualify for inclusion in the results- Returns:
- String[]
- Throws:
IOException- if the underlying index throws anIOExceptionAlreadyClosedException- if the Spellchecker is already closed- See Also:
suggestSimilar(String, int, IndexReader, String, SuggestMode, float)
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suggestSimilar
public String[] suggestSimilar(String word, int numSug, IndexReader ir, String field, SuggestMode suggestMode) throws IOException
- Throws:
IOException
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suggestSimilar
public String[] suggestSimilar(String word, int numSug, IndexReader ir, String field, SuggestMode suggestMode, float accuracy) throws IOException
Suggest similar words (optionally restricted to a field of an index).As the Lucene similarity that is used to fetch the most relevant n-grammed terms is not the same as the edit distance strategy used to calculate the best matching spell-checked word from the hits that Lucene found, one usually has to retrieve a couple of numSug's in order to get the true best match.
I.e. if numSug == 1, don't count on that suggestion being the best one. Thus, you should set this value to at least 5 for a good suggestion.
- Parameters:
word- the word you want a spell check done onnumSug- the number of suggested wordsir- the indexReader of the user index (can be null see field param)field- the field of the user index: if field is not null, the suggested words are restricted to the words present in this field.suggestMode- (NOTE: if indexReader==null and/or field==null, then this is overridden with SuggestMode.SUGGEST_ALWAYS)accuracy- The minimum score a suggestion must have in order to qualify for inclusion in the results- Returns:
- String[] the sorted list of the suggest words with these 2 criteria: first criteria: the edit distance, second criteria (only if restricted mode): the popularity of the suggest words in the field of the user index
- Throws:
IOException- if the underlying index throws anIOExceptionAlreadyClosedException- if the Spellchecker is already closed
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clearIndex
public void clearIndex() throws IOExceptionRemoves all terms from the spell check index.- Throws:
IOException- If there is a low-level I/O error.AlreadyClosedException- if the Spellchecker is already closed
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exist
public boolean exist(String word) throws IOException
Check whether the word exists in the index.- Parameters:
word- word to check- Returns:
- true if the word exists in the index
- Throws:
IOException- If there is a low-level I/O error.AlreadyClosedException- if the Spellchecker is already closed
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indexDictionary
public final void indexDictionary(Dictionary dict, IndexWriterConfig config, boolean fullMerge) throws IOException
Indexes the data from the givenDictionary.- Parameters:
dict- Dictionary to indexconfig-IndexWriterConfigto usefullMerge- whether or not the spellcheck index should be fully merged- Throws:
AlreadyClosedException- if the Spellchecker is already closedIOException- If there is a low-level I/O error.
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close
public void close() throws IOExceptionClose the IndexSearcher used by this SpellChecker- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Throws:
IOException- if the close operation causes anIOExceptionAlreadyClosedException- if theSpellCheckeris already closed
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