Class 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 Detail

      • FuzzyLikeThisQuery

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

      • 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"
        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)
      • isIgnoreTF

        public boolean isIgnoreTF()
      • setIgnoreTF

        public void setIgnoreTF​(boolean ignoreTF)