Class SimilarityDelegator

    • Constructor Detail

      • SimilarityDelegator

        public SimilarityDelegator​(Similarity delegee)
        Deprecated.
        Construct a Similarity that delegates all methods to another.
        Parameters:
        delegee - the Similarity implementation to delegate to
    • Method Detail

      • queryNorm

        public float queryNorm​(float sumOfSquaredWeights)
        Deprecated.
        Description copied from class: Similarity
        Computes the normalization value for a query given the sum of the squared weights of each of the query terms. This value is multiplied into the weight of each query term. While the classic query normalization factor is computed as 1/sqrt(sumOfSquaredWeights), other implementations might completely ignore sumOfSquaredWeights (ie return 1).

        This does not affect ranking, but the default implementation does make scores from different queries more comparable than they would be by eliminating the magnitude of the Query vector as a factor in the score.

        Specified by:
        queryNorm in class Similarity
        Parameters:
        sumOfSquaredWeights - the sum of the squares of query term weights
        Returns:
        a normalization factor for query weights
      • tf

        public float tf​(float freq)
        Deprecated.
        Description copied from class: Similarity
        Computes a score factor based on a term or phrase's frequency in a document. This value is multiplied by the Similarity.idf(int, int) factor for each term in the query and these products are then summed to form the initial score for a document.

        Terms and phrases repeated in a document indicate the topic of the document, so implementations of this method usually return larger values when freq is large, and smaller values when freq is small.

        Specified by:
        tf in class Similarity
        Parameters:
        freq - the frequency of a term within a document
        Returns:
        a score factor based on a term's within-document frequency
      • sloppyFreq

        public float sloppyFreq​(int distance)
        Deprecated.
        Description copied from class: Similarity
        Computes the amount of a sloppy phrase match, based on an edit distance. This value is summed for each sloppy phrase match in a document to form the frequency that is passed to Similarity.tf(float).

        A phrase match with a small edit distance to a document passage more closely matches the document, so implementations of this method usually return larger values when the edit distance is small and smaller values when it is large.

        Specified by:
        sloppyFreq in class Similarity
        Parameters:
        distance - the edit distance of this sloppy phrase match
        Returns:
        the frequency increment for this match
        See Also:
        PhraseQuery.setSlop(int)
      • idf

        public float idf​(int docFreq,
                         int numDocs)
        Deprecated.
        Description copied from class: Similarity
        Computes a score factor based on a term's document frequency (the number of documents which contain the term). This value is multiplied by the Similarity.tf(int) factor for each term in the query and these products are then summed to form the initial score for a document.

        Terms that occur in fewer documents are better indicators of topic, so implementations of this method usually return larger values for rare terms, and smaller values for common terms.

        Specified by:
        idf in class Similarity
        Parameters:
        docFreq - the number of documents which contain the term
        numDocs - the total number of documents in the collection
        Returns:
        a score factor based on the term's document frequency
      • coord

        public float coord​(int overlap,
                           int maxOverlap)
        Deprecated.
        Description copied from class: Similarity
        Computes a score factor based on the fraction of all query terms that a document contains. This value is multiplied into scores.

        The presence of a large portion of the query terms indicates a better match with the query, so implementations of this method usually return larger values when the ratio between these parameters is large and smaller values when the ratio between them is small.

        Specified by:
        coord in class Similarity
        Parameters:
        overlap - the number of query terms matched in the document
        maxOverlap - the total number of terms in the query
        Returns:
        a score factor based on term overlap with the query
      • scorePayload

        public float scorePayload​(int docId,
                                  String fieldName,
                                  int start,
                                  int end,
                                  byte[] payload,
                                  int offset,
                                  int length)
        Deprecated.
        Description copied from class: Similarity
        Calculate a scoring factor based on the data in the payload. Overriding implementations are responsible for interpreting what is in the payload. Lucene makes no assumptions about what is in the byte array.

        The default implementation returns 1.

        Overrides:
        scorePayload in class Similarity
        Parameters:
        docId - The docId currently being scored. If this value is Similarity.NO_DOC_ID_PROVIDED, then it should be assumed that the PayloadQuery implementation does not provide document information
        fieldName - The fieldName of the term this payload belongs to
        start - The start position of the payload
        end - The end position of the payload
        payload - The payload byte array to be scored
        offset - The offset into the payload array
        length - The length in the array
        Returns:
        An implementation dependent float to be used as a scoring factor