how do you get the matching fuzzy term and its offset when using Lucene Fuzzy Search?
IndexSearcher mem = ....(some standard code)
QueryParser parser = ne开发者_C百科w QueryParser(Version.LUCENE_30, CONTENT_FIELD, analyzer);
TopDocs topDocs = mem.search(parser.parse("wuzzy~"), 1);
// the ~ triggers the fuzzy search as per "Lucene In Action"
The fuzzy search works fine. If a document contains the term "fuzzy" or "luzzy", it is matched. How do I get which term matched and what are their offsets?
I have made sure that all CONTENT_FIELDs are added with termVectorStored with positions and offsets .
There was no straight forward way of doing this, however I reconsidered Jared's suggestion and was able to get the solution working.
I am documenting this here just in case someone else has the same issue.
Create a class that implements org.apache.lucene.search.highlight.Formatter
public class HitPositionCollector implements Formatter
{
// MatchOffset is a simple DTO
private List<MatchOffset> matchList;
public HitPositionCollector(
{
matchList = new ArrayList<MatchOffset>();
}
// this ie where the term start and end offset as well as the actual term is captured
@Override
public String highlightTerm(String originalText, TokenGroup tokenGroup)
{
if (tokenGroup.getTotalScore() <= 0)
{
}
else
{
MatchOffset mo= new MatchOffset(tokenGroup.getToken(0).toString(), tokenGroup.getStartOffset(),tokenGroup.getEndOffset());
getMatchList().add(mo);
}
return originalText;
}
/**
* @return the matchList
*/
public List<MatchOffset> getMatchList()
{
return matchList;
}
}
Main Code
public void testHitsWithHitPositionCollector() throws Exception
{
System.out.println(" .... testHitsWithHitPositionCollector");
String fuzzyStr = "bro*";
QueryParser parser = new QueryParser(Version.LUCENE_30, "f", analyzer);
Query fzyQry = parser.parse(fuzzyStr);
TopDocs hits = searcher.search(fzyQry, 10);
QueryScorer scorer = new QueryScorer(fzyQry, "f");
HitPositionCollector myFormatter= new HitPositionCollector();
//Highlighter(Formatter formatter, Scorer fragmentScorer)
Highlighter highlighter = new Highlighter(myFormatter,scorer);
highlighter.setTextFragmenter(
new SimpleSpanFragmenter(scorer)
);
Analyzer analyzer2 = new SimpleAnalyzer();
int loopIndex=0;
//for (ScoreDoc sd : hits.scoreDocs) {
Document doc = searcher.doc( hits.scoreDocs[0].doc);
String title = doc.get("f");
TokenStream stream = TokenSources.getAnyTokenStream(searcher.getIndexReader(),
hits.scoreDocs[0].doc,
"f",
doc,
analyzer2);
String fragment = highlighter.getBestFragment(stream, title);
System.out.println(fragment);
assertEquals("the quick brown fox jumps over the lazy dog", fragment);
MatchOffset mo= myFormatter.getMatchList().get(loopIndex++);
assertTrue(mo.getEndPos()==15);
assertTrue(mo.getStartPos()==10);
assertTrue(mo.getToken().equals("brown"));
}
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