Package org.apache.lucene.sandbox.queries

Class FuzzyLikeThisQuery

java.lang.Object
org.apache.lucene.search.Query
org.apache.lucene.sandbox.queries.FuzzyLikeThisQuery
public class FuzzyLikeThisQuery extends Query
Fuzzifies ALL terms provided as strings and then picks the best n differentiating terms. In effect this mixes the behaviour of 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 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.

  • Constructor Details

    • FuzzyLikeThisQuery

      public FuzzyLikeThisQuery(int maxNumTerms, Analyzer analyzer)
      Parameters:
      maxNumTerms - The total number of terms clauses that will appear once rewritten as a BooleanQuery

  • Method Details

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in class Query

    • equals

      public boolean equals(Object other)
      Specified by:
      equals in class Query

    • addTerms

      public void addTerms(String queryString, String fieldName, float minSimilarity, int prefixLength)
      Adds user input for "fuzzification"
      Parameters:
      queryString - The string which will be parsed by the analyzer and for which fuzzy variants will be parsed
      minSimilarity - 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)

    • visit

      public void visit(QueryVisitor visitor)
      Specified by:
      visit in class Query

    • rewrite

      public Query rewrite(IndexReader reader) throws IOException
      Overrides:
      rewrite in class Query
      Throws:
      IOException

    • toString

      public String toString(String field)
      Specified by:
      toString in class Query

    • isIgnoreTF

      public boolean isIgnoreTF()

    • setIgnoreTF

      public void setIgnoreTF(boolean ignoreTF)