org.apache.lucene.search

Class FuzzyQuery

java.lang.Object

org.apache.lucene.search.Query

org.apache.lucene.search.MultiTermQuery

org.apache.lucene.search.FuzzyQuery

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public class FuzzyQuery
extends MultiTermQuery

Implements the fuzzy search query. The similiarity measurement is based on the Levenshtein (edit distance) algorithm.

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	FuzzyQuery.ScoreTerm
protected static class	FuzzyQuery.ScoreTermQueue

Field Summary

Fields

Modifier and Type	Field and Description
static float	defaultMinSimilarity
static int	defaultPrefixLength

Constructor Summary

Constructors

Constructor and Description
FuzzyQuery(Term term) Calls FuzzyQuery(term, 0.5f, 0).
FuzzyQuery(Term term, float minimumSimilarity) Calls FuzzyQuery(term, minimumSimilarity, 0).
FuzzyQuery(Term term, float minimumSimilarity, int prefixLength) Create a new FuzzyQuery that will match terms with a similarity of at least minimumSimilarity to term.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(java.lang.Object o)
protected FilteredTermEnum	getEnum(IndexReader reader) Construct the enumeration to be used, expanding the pattern term.
float	getMinSimilarity() Returns the minimum similarity that is required for this query to match.
int	getPrefixLength() Returns the non-fuzzy prefix length.
int	hashCode()
Query	rewrite(IndexReader reader) Expert: called to re-write queries into primitive queries.
java.lang.String	toString(java.lang.String field) Prints a user-readable version of this query.

Methods inherited from class org.apache.lucene.search.MultiTermQuery

getTerm

Methods inherited from class org.apache.lucene.search.Query

clone, combine, createWeight, extractTerms, getBoost, getSimilarity, mergeBooleanQueries, setBoost, toString, weight

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

defaultMinSimilarity

public static final float defaultMinSimilarity

See Also:

Constant Field Values

defaultPrefixLength

public static final int defaultPrefixLength

See Also:

Constant Field Values

Constructor Detail

FuzzyQuery

public FuzzyQuery(Term term,
          float minimumSimilarity,
          int prefixLength)
           throws java.lang.IllegalArgumentException

Create a new FuzzyQuery that will match terms with a similarity of at least minimumSimilarity to term. If a prefixLength > 0 is specified, a common prefix of that length is also required.

Parameters:

term - the term to search for

minimumSimilarity - a value between 0 and 1 to set the required similarity between the query term and the matching terms. For example, for a minimumSimilarity of 0.5 a term of the same length as the query term is considered similar to the query term if the edit distance between both terms is less than length(term)*0.5

prefixLength - length of common (non-fuzzy) prefix

Throws:

java.lang.IllegalArgumentException - if minimumSimilarity is >= 1 or < 0 or if prefixLength < 0

FuzzyQuery

public FuzzyQuery(Term term,
          float minimumSimilarity)
           throws java.lang.IllegalArgumentException

Calls FuzzyQuery(term, minimumSimilarity, 0).

Throws:

java.lang.IllegalArgumentException

FuzzyQuery

public FuzzyQuery(Term term)

Calls FuzzyQuery(term, 0.5f, 0).

Method Detail

getMinSimilarity

public float getMinSimilarity()

Returns the minimum similarity that is required for this query to match.

Returns:

float value between 0.0 and 1.0

getPrefixLength

public int getPrefixLength()

Returns the non-fuzzy prefix length. This is the number of characters at the start of a term that must be identical (not fuzzy) to the query term if the query is to match that term.

getEnum

protected FilteredTermEnum getEnum(IndexReader reader)
                            throws java.io.IOException

Description copied from class: MultiTermQuery

Construct the enumeration to be used, expanding the pattern term.

Specified by:

getEnum in class MultiTermQuery

Throws:

java.io.IOException

rewrite

public Query rewrite(IndexReader reader)
              throws java.io.IOException

Description copied from class: Query

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

Overrides:

rewrite in class MultiTermQuery

Throws:

java.io.IOException

toString

public java.lang.String toString(java.lang.String field)

Description copied from class: MultiTermQuery

Prints a user-readable version of this query.

Overrides:

toString in class MultiTermQuery

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class MultiTermQuery

hashCode

public int hashCode()

Overrides:

hashCode in class MultiTermQuery