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
object
SpellChecker
Implements
Inherited Members
Namespace: Lucene.Net.Search.Spell
Assembly: Lucene.Net.Suggest.dll
Syntax
public class SpellChecker : IDisposable

Constructors

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
IOException

if spellchecker can not open the directory

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
IOException

if Spellchecker can not open the directory

SpellChecker(Directory, IStringDistance, IComparer<SuggestWord>)

Use the given directory as a spell checker index with the given IStringDistance measure and the given 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
IComparer<SuggestWord> comparer

The comparer
Exceptions
Type Condition
IOException

if there is a problem opening the index

Fields

DEFAULT_ACCURACY

The default minimum score to use, if not specified by setting Accuracy or overriding with SuggestSimilar(string, int, IndexReader, string, SuggestMode, float) .

Declaration
public const float DEFAULT_ACCURACY = 0.5
Field Value
Type Description
float

F_WORD

Field name for each word in the ngram index.

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

Properties

Accuracy

Gets or sets the accuracy (minimum score) to be used, unless overridden in SuggestSimilar(string, int, IndexReader, string, SuggestMode, float), 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
float

Comparer

Gets or sets the IComparer<T> for the SuggestWordQueue.

Declaration
public virtual IComparer<SuggestWord> Comparer { get; set; }
Property Value
Type Description
IComparer<SuggestWord>

StringDistance

Gets or sets the IStringDistance implementation for this SpellChecker instance.

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

Methods

ClearIndex()

Removes all terms from the spell check index.

Declaration
public virtual void ClearIndex()
Exceptions
Type Condition
IOException

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

if the Spellchecker is already closed

Dispose()

Dispose the underlying Lucene.Net.Search.IndexSearcher used by this SpellChecker.

Declaration
public void Dispose()
Exceptions
Type Condition
IOException

if the close operation causes an IOException
ObjectDisposedException

if the SpellChecker is already disposed

Dispose(bool)

Releases resources used by the SpellChecker and if overridden in a derived class, optionally releases unmanaged resources.

Declaration
protected virtual void Dispose(bool disposing)
Parameters
Type Name Description
bool disposing

true to release both managed and unmanaged resources; false to release only unmanaged resources.

Exist(string)

Check whether the word exists in the index.

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

word to check
Returns
Type Description
bool

true if the word exists in the index
Exceptions
Type Condition
IOException

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

if the SpellChecker is already disposed

IndexDictionary(IDictionary, IndexWriterConfig, bool)

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

Lucene.Net.Index.IndexWriterConfig to use
bool fullMerge

whether or not the spellcheck index should be fully merged
Exceptions
Type Condition
ObjectDisposedException

if the SpellChecker is already disposed
IOException

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

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 void SetSpellIndex(Directory spellIndexDir)
Parameters
Type Name Description
Directory spellIndexDir

the spell directory to use
Exceptions
Type Condition
ObjectDisposedException

if the Spellchecker is already closed
IOException

if spellchecker can not open the directory

SuggestSimilar(string, int)

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
string word

the word you want a spell check done on
int numSug

the number of suggested words
Returns
Type Description
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
IOException

if the underlying index throws an IOException
ObjectDisposedException

if the Spellchecker is already disposed
See Also

SuggestSimilar(string, int, IndexReader, string, SuggestMode)

Calls SuggestSimilar(string, int, IndexReader, string, SuggestMode, float) 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
string word
int numSug
IndexReader ir
string field
SuggestMode suggestMode
Returns
Type Description
string[]

SuggestSimilar(string, int, IndexReader, string, SuggestMode, float)

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
string word

the word you want a spell check done on
int numSug

the number of suggested words
IndexReader ir

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

The minimum score a suggestion must have in order to qualify for inclusion in the results
Returns
Type Description
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
IOException

if the underlying index throws an IOException
ObjectDisposedException

if the SpellChecker is already disposed

SuggestSimilar(string, int, float)

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
string word

the word you want a spell check done on
int numSug

the number of suggested words
float accuracy

The minimum score a suggestion must have in order to qualify for inclusion in the results
Returns
Type Description
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
IOException

if the underlying index throws an IOException
ObjectDisposedException

if the Spellchecker is already disposed
See Also

Implements