我在使用Lucene的评分功能时遇到了问题,但是我无法解决。到目前为止,我已经编写了以下代码来重现它。
package lucenebug;
import java.util.Arrays;
import java.util.List;
import org.apache.lucene.analysis.SimpleAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.queryParser.QueryParser;
import org.apache.lucene.search.IndexSearcher;
import org.apache.lucene.search.Query;
import org.apache.lucene.search.ScoreDoc;
import org.apache.lucene.search.TopDocs;
public class Test {
private static final String TMP_LUCENEBUG_INDEX = "/tmp/lucenebug_index";
public static void main(String[] args) throws Throwable {
SimpleAnalyzer analyzer = new SimpleAnalyzer();
IndexWriter w = new IndexWriter(TMP_LUCENEBUG_INDEX, analyzer, true);
List<String> names = Arrays
.asList(new String[] { "the rolling stones",
"rolling stones (karaoke)",
"the rolling stones tribute",
"rolling stones tribute band",
"karaoke - the rolling stones" });
try {
for (String name : names) {
System.out.println("#name: " + name);
Document doc = new Document();
doc.add(new Field("name", name, Field.Store.YES,
Field.Index.TOKENIZED));
w.addDocument(doc);
}
System.out.println("finished adding docs, total size: "
+ w.docCount());
} finally {
w.close();
}
IndexSearcher s = new IndexSearcher(TMP_LUCENEBUG_INDEX);
QueryParser p = new QueryParser("name", analyzer);
Query q = p.parse("name:(rolling stones)");
System.out.println("--------\nquery: " + q);
TopDocs topdocs = s.search(q, null, 10);
for (ScoreDoc sd : topdocs.scoreDocs) {
System.out.println("" + sd.score + "\t"
+ s.doc(sd.doc).getField("name").stringValue());
}
}
}
我运行它后得到的输出是:
finished adding docs, total size: 5
--------
query: name:rolling name:stones
0.578186 the rolling stones
0.578186 rolling stones (karaoke)
0.578186 the rolling stones tribute
0.578186 rolling stones tribute band
0.578186 karaoke - the rolling stones
我就是无法理解为什么“滚石乐队”和“滚石乐队致敬”具有相同的相关性。根据Lucene的文档,字段中的标记数量越多,规范化因子就应该越小,因此“滚石乐队致敬”应该比“滚石乐队”得分更低。
有什么想法吗?