For each source term the fuzzy variants are held in a BooleanQuery with no coord factor (because we are not looking for matches on multiple variants in any one doc). Additionally, a specialized 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.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescription(package private) static class
private static class
private static class
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Field Summary
FieldsModifier and TypeFieldDescription(package private) Analyzer
(package private) ArrayList<FuzzyLikeThisQuery.FieldVals>
(package private) boolean
(package private) int
private int
(package private) static TFIDFSimilarity
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionvoid
Adds user input for "fuzzification"private void
boolean
Override and implement query instance equivalence properly in a subclass.private boolean
equalsTo
(FuzzyLikeThisQuery other) int
hashCode()
Override and implement query hash code properly in a subclass.boolean
private Query
newTermQuery
(IndexReader reader, Term term) rewrite
(IndexReader reader) Expert: called to re-write queries into primitive queries.void
setIgnoreTF
(boolean ignoreTF) Prints a query to a string, withfield
assumed to be the default field and omitted.void
visit
(QueryVisitor visitor) Recurse through the query tree, visiting any child queriesMethods inherited from class org.apache.lucene.search.Query
classHash, createWeight, sameClassAs, toString
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Field Details
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sim
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fieldVals
ArrayList<FuzzyLikeThisQuery.FieldVals> fieldVals -
analyzer
Analyzer analyzer -
MAX_VARIANTS_PER_TERM
int MAX_VARIANTS_PER_TERM -
ignoreTF
boolean ignoreTF -
maxNumTerms
private int maxNumTerms
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Constructor Details
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FuzzyLikeThisQuery
- Parameters:
maxNumTerms
- The total number of terms clauses that will appear once rewritten as a BooleanQuery
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Method Details
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hashCode
public int hashCode()Description copied from class:Query
Override and implement query hash code properly in a subclass. This is required so thatQueryCache
works properly. -
equals
Description copied from class:Query
Override and implement query instance equivalence properly in a subclass. This is required so thatQueryCache
works properly.Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.
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equalsTo
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addTerms
Adds user input for "fuzzification"- Parameters:
queryString
- The string which will be parsed by the analyzer and for which fuzzy variants will be parsedminSimilarity
- The minimum similarity of the term variants; must be 0, 1 or 2 (see FuzzyTermsEnum)prefixLength
- Length of required common prefix on variant terms (see FuzzyTermsEnum)
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addTerms
private void addTerms(IndexReader reader, FuzzyLikeThisQuery.FieldVals f, FuzzyLikeThisQuery.ScoreTermQueue q) throws IOException - Throws:
IOException
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newTermQuery
- Throws:
IOException
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visit
Description copied from class:Query
Recurse through the query tree, visiting any child queries -
rewrite
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.Callers are expected to call
rewrite
multiple times if necessary, until the rewritten query is the same as the original query.- Overrides:
rewrite
in classQuery
- Throws:
IOException
- See Also:
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toString
Description copied from class:Query
Prints a query to a string, withfield
assumed to be the default field and omitted. -
isIgnoreTF
public boolean isIgnoreTF() -
setIgnoreTF
public void setIgnoreTF(boolean ignoreTF)
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