Class FuzzyLikeThisQuery

Fuzzifies ALL terms provided as strings and then picks the best n differentiating terms. In effect this mixes the behaviour of Lucene.Net.Search.FuzzyQuery and MoreLikeThis but with special consideration of fuzzy scoring factors. This generally produces good results for queries where users may provide details in a number of fields and have no knowledge of boolean query syntax and also want a degree of fuzzy matching and a fast query.

For each source term the fuzzy variants are held in a Lucene.Net.Search.BooleanQuery with no coord factor (because we are not looking for matches on multiple variants in any one doc). Additionally, a specialized Lucene.Net.Search.TermQuery is used for variants and does not use that variant term's IDF because this would favour rarer terms eg misspellings. Instead, all variants use the same IDF ranking (the one for the source query term) and this is factored into the variant's boost. If the source query term does not exist in the index the average IDF of the variants is used.

Inheritance

object

Query

FuzzyLikeThisQuery

Inherited Members

Query.Boost

Query.ToString()

Query.CreateWeight(IndexSearcher)

Query.ExtractTerms(ISet<Term>)

Query.Clone()

object.Equals(object, object)

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

Namespace: Lucene.Net.Sandbox.Queries

Assembly: Lucene.Net.Sandbox.dll

Syntax

public class FuzzyLikeThisQuery : Query

Constructors

FuzzyLikeThisQuery(int, Analyzer)

Declaration

public FuzzyLikeThisQuery(int maxNumTerms, Analyzer analyzer)

Parameters

Type	Name	Description
int	maxNumTerms	The total number of terms clauses that will appear once rewritten as a Lucene.Net.Search.BooleanQuery
Analyzer	analyzer

Properties

IgnoreTF

Declaration

public virtual bool IgnoreTF { get; set; }

Property Value

Type	Description
bool

Methods

AddTerms(string, string, float, int)

Adds user input for "fuzzification"

Declaration

public virtual void AddTerms(string queryString, string fieldName, float minSimilarity, int prefixLength)

Parameters

Type	Name	Description
string	queryString	The string which will be parsed by the analyzer and for which fuzzy variants will be parsed
string	fieldName	The minimum similarity of the term variants (see Lucene.Net.Search.FuzzyTermsEnum)
float	minSimilarity	Length of required common prefix on variant terms (see Lucene.Net.Search.FuzzyTermsEnum)
int	prefixLength

Equals(object)

Determines whether the specified object is equal to the current object.

Declaration

public override bool Equals(object obj)

Parameters

Type	Name	Description
object	obj	The object to compare with the current object.

Returns

Type	Description
bool	true if the specified object is equal to the current object; otherwise, false.

Overrides

Query.Equals(object)

GetHashCode()

Serves as the default hash function.

Declaration

public override int GetHashCode()

Returns

Type	Description
int	A hash code for the current object.

Overrides

Lucene.Net.Search.Query.GetHashCode()

Rewrite(IndexReader)

Expert: called to re-write queries into primitive queries. For example, a Lucene.Net.Search.PrefixQuery will be rewritten into a Lucene.Net.Search.BooleanQuery that consists of Lucene.Net.Search.TermQuerys.

Declaration

public override Query Rewrite(IndexReader reader)

Parameters

Type	Name	Description
IndexReader	reader

Returns

Type	Description
Query

Overrides

Lucene.Net.Search.Query.Rewrite(Lucene.Net.Index.IndexReader)

ToString(string)

(non-Javadoc) ToString(string)

Declaration

public override string ToString(string field)

Parameters

Type	Name	Description
string	field

Returns

Type	Description
string

Overrides

Query.ToString(string)