Class SpellChecker

Spell Checker class (Main class)
(initially inspired by the David Spencer code).

Example Usage (C#): 

 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 FileInfo("myfile.txt")));
 string[] suggestions = spellchecker.SuggestSimilar("misspelt", 5);

Inheritance
System.Object
SpellChecker
Implements
System.IDisposable
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Namespace: Lucene.Net.Search.Spell
Assembly: Lucene.Net.Suggest.dll
Syntax
public class SpellChecker : IDisposable

Constructors

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SpellChecker(Directory)

Use the given directory as a spell checker index with a LevensteinDistance as the default StringDistance. The directory is created if it doesn't exist yet.

Declaration
public SpellChecker(Directory spellIndex)
Parameters
Type Name Description
Directory spellIndex

the spell index directory

Exceptions
Type Condition
System.IO.IOException

if spellchecker can not open the directory

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SpellChecker(Directory, IStringDistance)

Use the given directory as a spell checker index. The directory is created if it doesn't exist yet.

Declaration
public SpellChecker(Directory spellIndex, IStringDistance sd)
Parameters
Type Name Description
Directory spellIndex

the spell index directory

IStringDistance sd

the StringDistance measurement to use

Exceptions
Type Condition
System.IO.IOException

if Spellchecker can not open the directory

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SpellChecker(Directory, IStringDistance, IComparer<SuggestWord>)

Use the given directory as a spell checker index with the given IStringDistance measure and the given System.Collections.Generic.IComparer<T> for sorting the results.

Declaration
public SpellChecker(Directory spellIndex, IStringDistance sd, IComparer<SuggestWord> comparer)
Parameters
Type Name Description
Directory spellIndex

The spelling index

IStringDistance sd

The distance

System.Collections.Generic.IComparer<SuggestWord> comparer

The comparer

Exceptions
Type Condition
System.IO.IOException

if there is a problem opening the index

Fields

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DEFAULT_ACCURACY

The default minimum score to use, if not specified by setting Accuracy or overriding with SuggestSimilar(String, Int32, IndexReader, String, SuggestMode, Single) .

Declaration
public const float DEFAULT_ACCURACY = 0.5F
Field Value
Type Description
System.Single
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F_WORD

Field name for each word in the ngram index.

Declaration
public const string F_WORD = "word"
Field Value
Type Description
System.String

Properties

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Accuracy

Gets or sets the accuracy (minimum score) to be used, unless overridden in SuggestSimilar(String, Int32, IndexReader, String, SuggestMode, Single), to decide whether a suggestion is included or not. Sets the accuracy 0 < minScore < 1; default DEFAULT_ACCURACY

Declaration
public virtual float Accuracy { get; set; }
Property Value
Type Description
System.Single
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Comparer

Gets or sets the System.Collections.Generic.IComparer<T> for the SuggestWordQueue.

Declaration
public virtual IComparer<SuggestWord> Comparer { get; set; }
Property Value
Type Description
System.Collections.Generic.IComparer<SuggestWord>
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StringDistance

Gets or sets the IStringDistance implementation for this SpellChecker instance.

Declaration
public virtual IStringDistance StringDistance { get; set; }
Property Value
Type Description
IStringDistance

Methods

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ClearIndex()

Removes all terms from the spell check index.

Declaration
public virtual void ClearIndex()
Exceptions
Type Condition
System.IO.IOException

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

System.ObjectDisposedException

if the Spellchecker is already closed

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Dispose()

Dispose the underlying IndexSearcher used by this SpellChecker

Declaration
public void Dispose()
Exceptions
Type Condition
System.IO.IOException

if the close operation causes an System.IO.IOException

System.ObjectDisposedException

if the SpellChecker is already disposed

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Exist(String)

Check whether the word exists in the index.

Declaration
public virtual bool Exist(string word)
Parameters
Type Name Description
System.String word

word to check

Returns
Type Description
System.Boolean

true if the word exists in the index

Exceptions
Type Condition
System.IO.IOException

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

System.ObjectDisposedException

if the SpellChecker is already disposed

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IndexDictionary(IDictionary, IndexWriterConfig, Boolean)

Indexes the data from the given IDictionary.

Declaration
public void IndexDictionary(IDictionary dict, IndexWriterConfig config, bool fullMerge)
Parameters
Type Name Description
IDictionary dict

Dictionary to index

IndexWriterConfig config

IndexWriterConfig to use

System.Boolean fullMerge

whether or not the spellcheck index should be fully merged

Exceptions
Type Condition
System.ObjectDisposedException

if the SpellChecker is already disposed

System.IO.IOException

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

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SetSpellIndex(Directory)

Sets a different index as the spell checker index or re-open the existing index if 

spellIndex
is the same value as given in the constructor.

Declaration
public virtual void SetSpellIndex(Directory spellIndexDir)
Parameters
Type Name Description
Directory spellIndexDir

the spell directory to use

Exceptions
Type Condition
System.ObjectDisposedException

if the Spellchecker is already closed

System.IO.IOException

if spellchecker can not open the directory

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SuggestSimilar(String, Int32)

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.

Declaration
public virtual string[] SuggestSimilar(string word, int numSug)
Parameters
Type Name Description
System.String word

the word you want a spell check done on

System.Int32 numSug

the number of suggested words

Returns
Type Description
System.String[]

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
Exceptions
Type Condition
System.IO.IOException

if the underlying index throws an System.IO.IOException

System.ObjectDisposedException

if the Spellchecker is already disposed

See Also
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SuggestSimilar(String, Int32, IndexReader, String, SuggestMode)

Calls SuggestSimilar(String, Int32, IndexReader, String, SuggestMode, Single) SuggestSimilar(word, numSug, ir, suggestMode, field, this.accuracy)

Declaration
public virtual string[] SuggestSimilar(string word, int numSug, IndexReader ir, string field, SuggestMode suggestMode)
Parameters
Type Name Description
System.String word
System.Int32 numSug
IndexReader ir
System.String field
SuggestMode suggestMode
Returns
Type Description
System.String[]
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SuggestSimilar(String, Int32, IndexReader, String, SuggestMode, Single)

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.

Declaration
public virtual string[] SuggestSimilar(string word, int numSug, IndexReader ir, string field, SuggestMode suggestMode, float accuracy)
Parameters
Type Name Description
System.String word

the word you want a spell check done on

System.Int32 numSug

the number of suggested words

IndexReader ir

the indexReader of the user index (can be null see field param)

System.String 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 suggestMode

(NOTE: if indexReader==null and/or field==null, then this is overridden with SuggestMode.SUGGEST_ALWAYS)

System.Single accuracy

The minimum score a suggestion must have in order to qualify for inclusion in the results

Returns
Type Description
System.String[]

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
Exceptions
Type Condition
System.IO.IOException

if the underlying index throws an System.IO.IOException

System.ObjectDisposedException

if the SpellChecker is already disposed

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SuggestSimilar(String, Int32, Single)

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.

Declaration
public virtual string[] SuggestSimilar(string word, int numSug, float accuracy)
Parameters
Type Name Description
System.String word

the word you want a spell check done on

System.Int32 numSug

the number of suggested words

System.Single accuracy

The minimum score a suggestion must have in order to qualify for inclusion in the results

Returns
Type Description
System.String[]

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
Exceptions
Type Condition
System.IO.IOException

if the underlying index throws an System.IO.IOException

System.ObjectDisposedException

if the Spellchecker is already disposed

See Also

Implements

System.IDisposable