org.opencms.search
Class CmsSearchSimilarity

java.lang.Object
  org.apache.lucene.search.Similarity
      org.apache.lucene.search.DefaultSimilarity
          org.opencms.search.CmsSearchSimilarity

All Implemented Interfaces:

java.io.Serializable

public class CmsSearchSimilarity
extends org.apache.lucene.search.DefaultSimilarity

Reduces the importance of the lengthNorm(String, int) factor for the CmsSearchField.FIELD_CONTENT field, while keeping the Lucene default for all other fields.

This implementation was added since apparently the default length norm is heavily biased for small documents. In the default, even if a term is found in 2 documents the same number of times, the smaller document (containing less terms) will have a score easily 3x as high as the longer document. Using this implementation the importance of the term number is reduced.

Inspired by Chuck Williams WikipediaSimilarity.

Since:

6.0.0

Version:

$Revision: 1.12 $

Author:

Alexander Kandzior

See Also:

Serialized Form

Constructor Summary

CmsSearchSimilarity()
Creates a new instance of the OpenCms search similarity.

Method Summary

float

lengthNorm(java.lang.String fieldName, int numTerms) Special implementation for "length norm" to reduce the significance of this factor for the CmsSearchField.FIELD_CONTENT field, while keeping the Lucene default for all other fields.

Methods inherited from class org.apache.lucene.search.DefaultSimilarity

coord, idf, queryNorm, sloppyFreq, tf

Methods inherited from class org.apache.lucene.search.Similarity

decodeNorm, encodeNorm, getDefault, getNormDecoder, idf, idf, scorePayload, setDefault, tf

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CmsSearchSimilarity

public CmsSearchSimilarity()

Creates a new instance of the OpenCms search similarity.

Method Detail

lengthNorm

public float lengthNorm(java.lang.String fieldName,
                        int numTerms)

Special implementation for "length norm" to reduce the significance of this factor for the CmsSearchField.FIELD_CONTENT field, while keeping the Lucene default for all other fields.

Overrides:

lengthNorm in class org.apache.lucene.search.DefaultSimilarity

See Also:

Similarity.lengthNorm(java.lang.String, int)