FileDocCategorySizeDatePackage
SpanWeight.javaAPI DocApache Lucene 2.1.05047Wed Feb 14 10:46:38 GMT 2007org.apache.lucene.search.spans

SpanWeight

public class SpanWeight extends Object implements Weight
Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements. See the NOTICE file distributed with this work for additional information regarding copyright ownership. The ASF licenses this file to You under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Fields Summary
private Similarity
similarity
private float
value
private float
idf
private float
queryNorm
private float
queryWeight
private Set
terms
private SpanQuery
query
Constructors Summary
public SpanWeight(SpanQuery query, Searcher searcher)

    this.similarity = query.getSimilarity(searcher);
    this.query = query;
    terms=new HashSet();
    query.extractTerms(terms);

    idf = this.query.getSimilarity(searcher).idf(terms, searcher);
  
Methods Summary
public org.apache.lucene.search.Explanationexplain(org.apache.lucene.index.IndexReader reader, int doc)


    ComplexExplanation result = new ComplexExplanation();
    result.setDescription("weight("+getQuery()+" in "+doc+"), product of:");
    String field = ((SpanQuery)getQuery()).getField();

    StringBuffer docFreqs = new StringBuffer();
    Iterator i = terms.iterator();
    while (i.hasNext()) {
      Term term = (Term)i.next();
      docFreqs.append(term.text());
      docFreqs.append("=");
      docFreqs.append(reader.docFreq(term));

      if (i.hasNext()) {
        docFreqs.append(" ");
      }
    }

    Explanation idfExpl =
      new Explanation(idf, "idf(" + field + ": " + docFreqs + ")");

    // explain query weight
    Explanation queryExpl = new Explanation();
    queryExpl.setDescription("queryWeight(" + getQuery() + "), product of:");

    Explanation boostExpl = new Explanation(getQuery().getBoost(), "boost");
    if (getQuery().getBoost() != 1.0f)
      queryExpl.addDetail(boostExpl);
    queryExpl.addDetail(idfExpl);

    Explanation queryNormExpl = new Explanation(queryNorm,"queryNorm");
    queryExpl.addDetail(queryNormExpl);

    queryExpl.setValue(boostExpl.getValue() *
                       idfExpl.getValue() *
                       queryNormExpl.getValue());

    result.addDetail(queryExpl);

    // explain field weight
    ComplexExplanation fieldExpl = new ComplexExplanation();
    fieldExpl.setDescription("fieldWeight("+field+":"+query.toString(field)+
                             " in "+doc+"), product of:");

    Explanation tfExpl = scorer(reader).explain(doc);
    fieldExpl.addDetail(tfExpl);
    fieldExpl.addDetail(idfExpl);

    Explanation fieldNormExpl = new Explanation();
    byte[] fieldNorms = reader.norms(field);
    float fieldNorm =
      fieldNorms!=null ? Similarity.decodeNorm(fieldNorms[doc]) : 0.0f;
    fieldNormExpl.setValue(fieldNorm);
    fieldNormExpl.setDescription("fieldNorm(field="+field+", doc="+doc+")");
    fieldExpl.addDetail(fieldNormExpl);

    fieldExpl.setMatch(Boolean.valueOf(tfExpl.isMatch()));
    fieldExpl.setValue(tfExpl.getValue() *
                       idfExpl.getValue() *
                       fieldNormExpl.getValue());

    result.addDetail(fieldExpl);
    result.setMatch(fieldExpl.getMatch());

    // combine them
    result.setValue(queryExpl.getValue() * fieldExpl.getValue());

    if (queryExpl.getValue() == 1.0f)
      return fieldExpl;

    return result;
  
public org.apache.lucene.search.QuerygetQuery()

 return query; 
public floatgetValue()

 return value; 
public voidnormalize(float queryNorm)

    this.queryNorm = queryNorm;
    queryWeight *= queryNorm;                     // normalize query weight
    value = queryWeight * idf;                    // idf for document
  
public org.apache.lucene.search.Scorerscorer(org.apache.lucene.index.IndexReader reader)

    return new SpanScorer(query.getSpans(reader), this,
                          similarity,
                          reader.norms(query.getField()));
  
public floatsumOfSquaredWeights()

    queryWeight = idf * query.getBoost();         // compute query weight
    return queryWeight * queryWeight;             // square it