Class FuzzyLikeThisQuery

  • All Implemented Interfaces:
    Serializable, Cloneable

    public class FuzzyLikeThisQuery
    extends org.apache.lucene.search.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.
    See Also:
    Serialized Form
    • Constructor Detail

      • FuzzyLikeThisQuery

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

      • hashCode

        public int hashCode()
        Overrides:
        hashCode in class org.apache.lucene.search.Query
      • equals

        public boolean equals​(Object obj)
        Overrides:
        equals in class org.apache.lucene.search.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
        fieldName -
        minSimilarity - The minimum similarity of the term variants (see FuzzyTermEnum)
        prefixLength - Length of required common prefix on variant terms (see FuzzyTermEnum)
      • rewrite

        public org.apache.lucene.search.Query rewrite​(org.apache.lucene.index.IndexReader reader)
                                               throws IOException
        Overrides:
        rewrite in class org.apache.lucene.search.Query
        Throws:
        IOException
      • toString

        public String toString​(String field)
        Specified by:
        toString in class org.apache.lucene.search.Query
      • isIgnoreTF

        public boolean isIgnoreTF()
      • setIgnoreTF

        public void setIgnoreTF​(boolean ignoreTF)