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Posted to dev@lucene.apache.org by "sebastian L. (Issue Comment Edited) (JIRA)" <ji...@apache.org> on 2011/11/23 16:43:39 UTC
[jira] [Issue Comment Edited] (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=13155924#comment-13155924 ]
sebastian L. edited comment on LUCENE-3440 at 11/23/11 3:42 PM:
----------------------------------------------------------------
Patch for trunk 1205430. Works for me so far.
- Test fixed
- New test case "WeightedFragListBuilderTest"
was (Author: mdz-munich):
Patch trunk 1205430. Works for me sa far,
- Test fixed
- New test case "WeightedFragListBuilderTest"
> 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, 4.0
> Reporter: sebastian L.
> Priority: Minor
> Labels: FastVectorHighlighter
> Fix For: 3.5, 4.0
>
> Attachments: LUCENE-3440.patch, LUCENE-3440.patch, LUCENE-4.0-SNAPSHOT-3440-9.patch, weight-vs-boost_table01.html, weight-vs-boost_table02.html
>
>
> 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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