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https://issues.apache.org/jira/browse/LUCENE-3440?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13113873#comment-13113873
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Koji Sekiguchi commented on LUCENE-3440:
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Patch looks great! A few comments:
# For the new totalWeight, add getter method and modify toString() in
WeightedFragInfo().
# The patch uses hard-coded DefaultSimilarity to calculate idf. I don't think
that a custom similarity can be used here, too. If so, how about just copying
idf method rather than creating a similarity object?
# Please do not hesitate to update ScoreComparator (do not add
WeightOrderFragmentsBuilder)
# Could you update package javadoc (
https://builds.apache.org//job/Lucene-trunk/javadoc/contrib-highlighter/org/apache/lucene/search/vectorhighlight/package-summary.html#package_description
) and insert totalWeight into description and figures.
# use docFreq(String field, BytesRef term) version for trunk to avoid creating
Term object.
bq. Due to a significant lack of mathematical knowledge, a very intuitive
solution.
I agree. I think if there is a table so that we can compare totalBoost
(current) and totalWeight (patch) with real values, it helps a lot.
> 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: FastVectorHighlighter
> Fix For: 3.5
>
> Attachments: LUCENE-3.5-SNAPSHOT-3440-3.patch,
> LUCENE-4.0-SNAPSHOT-3440-3.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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