Class FuzzySuggester

Implements a fuzzy AnalyzingSuggester. The similarity measurement is based on the Damerau-Levenshtein (optimal string alignment) algorithm, though you can explicitly choose classic Levenshtein by passing false for the Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.transpositions parameter.

At most, this query will match terms up to edits. Higher distances are not supported. Note that the fuzzy distance is measured in "byte space" on the bytes returned by the 's , usually UTF8. By default the analyzed bytes must be at least 3 DEFAULT_MIN_FUZZY_LENGTH bytes before any edits are considered. Furthermore, the first 1 DEFAULT_NON_FUZZY_PREFIX byte is not allowed to be edited. We allow up to 1 DEFAULT_MAX_EDITS edit. If Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.unicodeAware parameter in the constructor is set to true, maxEdits, minFuzzyLength, transpositions and nonFuzzyPrefix are measured in Unicode code points (actual letters) instead of bytes.

NOTE: This suggester does not boost suggestions that required no edits over suggestions that did require edits. This is a known limitation.

Note: complex query analyzers can have a significant impact on the lookup performance. It's recommended to not use analyzers that drop or inject terms like synonyms to keep the complexity of the prefix intersection low for good lookup performance. At index time, complex analyzers can safely be used.

This is a Lucene.NET EXPERIMENTAL API, use at your own risk

Inheritance

System.Object

Lookup

AnalyzingSuggester

FuzzySuggester

Inherited Members

AnalyzingSuggester.GetSizeInBytes()

AnalyzingSuggester.Build(IInputIterator)

AnalyzingSuggester.Store(DataOutput)

AnalyzingSuggester.Load(DataInput)

AnalyzingSuggester.DoLookup(String, IEnumerable<BytesRef>, Boolean, Int32)

AnalyzingSuggester.Count

AnalyzingSuggester.Get(String)

Lookup.CHARSEQUENCE_COMPARER

Lookup.Build(IDictionary)

Lookup.Load(Stream)

Lookup.Store(Stream)

Lookup.DoLookup(String, Boolean, Int32)

Namespace: Lucene.Net.Search.Suggest.Analyzing

Assembly: Lucene.Net.Suggest.dll

Syntax

public sealed class FuzzySuggester : AnalyzingSuggester

Constructors

FuzzySuggester(Analyzer)

Creates a FuzzySuggester instance initialized with default values.

Declaration

public FuzzySuggester(Analyzer analyzer)

Parameters

Type	Name	Description
Analyzer	analyzer	The used for this suggester.

FuzzySuggester(Analyzer, Analyzer)

Creates a FuzzySuggester instance with an index & a query analyzer initialized with default values.

Declaration

public FuzzySuggester(Analyzer indexAnalyzer, Analyzer queryAnalyzer)

Parameters

Type	Name	Description
Analyzer	indexAnalyzer	that will be used for analyzing suggestions while building the index.
Analyzer	queryAnalyzer	that will be used for analyzing query text during lookup

FuzzySuggester(Analyzer, Analyzer, SuggesterOptions, Int32, Int32, Boolean, Int32, Boolean, Int32, Int32, Boolean)

Creates a FuzzySuggester instance.

Declaration

public FuzzySuggester(Analyzer indexAnalyzer, Analyzer queryAnalyzer, SuggesterOptions options, int maxSurfaceFormsPerAnalyzedForm, int maxGraphExpansions, bool preservePositionIncrements, int maxEdits, bool transpositions, int nonFuzzyPrefix, int minFuzzyLength, bool unicodeAware)

Parameters

Type	Name	Description
Analyzer	indexAnalyzer	The that will be used for analyzing suggestions while building the index.
Analyzer	queryAnalyzer	The that will be used for analyzing query text during lookup
SuggesterOptions	options	see EXACT_FIRST, PRESERVE_SEP
System.Int32	maxSurfaceFormsPerAnalyzedForm	Maximum number of surface forms to keep for a single analyzed form. When there are too many surface forms we discard the lowest weighted ones.
System.Int32	maxGraphExpansions	Maximum number of graph paths to expand from the analyzed form. Set this to -1 for no limit.
System.Boolean	preservePositionIncrements	Whether position holes should appear in the automaton
System.Int32	maxEdits	must be >= 0 and <= .
System.Boolean	transpositions	true if transpositions should be treated as a primitive edit operation. If this is false, comparisons will implement the classic Levenshtein algorithm.
System.Int32	nonFuzzyPrefix	length of common (non-fuzzy) prefix (see default DEFAULT_NON_FUZZY_PREFIX
System.Int32	minFuzzyLength	minimum length of lookup key before any edits are allowed (see default DEFAULT_MIN_FUZZY_LENGTH)
System.Boolean	unicodeAware	operate Unicode code points instead of bytes.

Fields

DEFAULT_MAX_EDITS

The default maximum number of edits for fuzzy suggestions.

Declaration

public const int DEFAULT_MAX_EDITS = null

Field Value

Type	Description
System.Int32

DEFAULT_MIN_FUZZY_LENGTH

The default minimum length of the key passed to Lookup before any edits are allowed.

Declaration

public const int DEFAULT_MIN_FUZZY_LENGTH = null

Field Value

Type	Description
System.Int32

DEFAULT_NON_FUZZY_PREFIX

The default prefix length where edits are not allowed.

Declaration

public const int DEFAULT_NON_FUZZY_PREFIX = null

Field Value

Type	Description
System.Int32

DEFAULT_TRANSPOSITIONS

The default transposition value passed to

Declaration

public const bool DEFAULT_TRANSPOSITIONS = null

Field Value

Type	Description
System.Boolean

DEFAULT_UNICODE_AWARE

Measure Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.maxEdits, Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.minFuzzyLength, Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.transpositions, and Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.nonFuzzyPrefix parameters in Unicode code points (actual letters) instead of bytes.

Declaration

public const bool DEFAULT_UNICODE_AWARE = null

Field Value

Type	Description
System.Boolean

Methods

ConvertAutomaton(Automaton)

Declaration

protected override Automaton ConvertAutomaton(Automaton a)

Parameters

Type	Name	Description
Automaton	a

Returns

Type	Description
Automaton

Overrides

AnalyzingSuggester.ConvertAutomaton(Automaton)

GetFullPrefixPaths(IList<FSTUtil.Path<PairOutputs<Nullable<Int64>, BytesRef>.Pair>>, Automaton, FST<PairOutputs<Nullable<Int64>, BytesRef>.Pair>)

Declaration

protected override IList<FSTUtil.Path<PairOutputs<long?, BytesRef>.Pair>> GetFullPrefixPaths(IList<FSTUtil.Path<PairOutputs<long?, BytesRef>.Pair>> prefixPaths, Automaton lookupAutomaton, FST<PairOutputs<long?, BytesRef>.Pair> fst)

Parameters

Type	Name	Description
IList<FSTUtil.Path<PairOutputs.Pair<>>>	prefixPaths
Automaton	lookupAutomaton
FST<PairOutputs.Pair<>>	fst

Returns

Type	Description
IList<FSTUtil.Path<PairOutputs.Pair<>>>

Overrides

AnalyzingSuggester.GetFullPrefixPaths(IList<FSTUtil.Path<PairOutputs<Nullable<Int64>, BytesRef>.Pair>>, Automaton, FST<PairOutputs<Nullable<Int64>, BytesRef>.Pair>)