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Posted to dev@lucene.apache.org by "Koji Sekiguchi (JIRA)" <ji...@apache.org> on 2011/09/22 02:33:27 UTC
[jira] [Commented] (LUCENE-3440) FastVectorHighlighter:
IDF-weighted terms for ordered fragments
[ https://issues.apache.org/jira/browse/LUCENE-3440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13112261#comment-13112261 ]
Koji Sekiguchi commented on LUCENE-3440:
----------------------------------------
I think this is an interesting point of view, thanks! But I couldn't apply the patch to the latest trunk:
{code}
[koji@MacBook LUCENE-3440]$ patch -p0 --dry-run < LUCENE-3440.patch
patching file lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldFragList.java
patching file lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldPhraseList.java
patching file lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldTermStack.java
Hunk #1 FAILED at 31.
Hunk #2 FAILED at 96.
Hunk #3 FAILED at 108.
Hunk #4 succeeded at 148 (offset -9 lines).
3 out of 4 hunks FAILED -- saving rejects to file lucene/contrib/highlighter/src/java/org/apache/lucene/search/vectorhighlight/FieldTermStack.java.rej
{code}
Can you verify that?
> FastVectorHighlighter: IDF-weighted terms for ordered fragments
> ----------------------------------------------------------------
>
> Key: LUCENE-3440
> URL: https://issues.apache.org/jira/browse/LUCENE-3440
> Project: Lucene - Java
> Issue Type: Improvement
> Components: modules/highlighter
> Affects Versions: 3.5
> Reporter: S.L.
> Priority: Minor
> Labels: patch
> Fix For: 3.5
>
> Attachments: LUCENE-3440-1.patch
>
>
> The FastVectorHighlighter uses for every term found in a fragment an equal weight, which causes a higher ranking for fragments with a high number of words or, in the worst case, a high number of very common words than fragments that contains *all* of the terms used in the original query.
> This patch provides ordered fragments with IDF-weighted terms:
> total weight = total weight + IDF for unique term per fragment * boost of query;
> The ranking-formula should be the same, or at least similar, to that one used in org.apache.lucene.search.highlight.QueryTermScorer.
> The patch is simple, but it works for us.
> Some ideas:
> - A better approach would be moving the whole fragments-scoring into a separate class.
> - Switch scoring via parameter
> - Exact phrases should be given a even better score, regardless if a phrase-query was executed or not
> - edismax/dismax-parameters pf, ps and pf^boost should be observed and corresponding fragments should be ranked higher
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