[jira] Commented: (NUTCH-134) Summarizer doesn't select the best snippets

["Chris Fellows (JIRA)" <ji...@apache.org>]

    [ http://issues.apache.org/jira/browse/NUTCH-134?page=comments#action_12377654 ] 

Chris Fellows commented on NUTCH-134:
-------------------------------------

byron,

Did you ever get a chance to run a cpu perf test on using lucene/contrib/highlighter for extracting summaries?

chris

> Summarizer doesn't select the best snippets
> -------------------------------------------
>
>          Key: NUTCH-134
>          URL: http://issues.apache.org/jira/browse/NUTCH-134
>      Project: Nutch
>         Type: Bug

>   Components: searcher
>     Versions: 0.7.2, 0.7.1, 0.7, 0.8-dev
>     Reporter: Andrzej Bialecki 

>
> Summarizer.java tries to select the best fragments from the input text, where the frequency of query terms is the highest. However, the logic in line 223 is flawed in that the excerptSet.add() operation will add new excerpts only if they are not already present - the test is performed using the Comparator that compares only the numUniqueTokens. This means that if there are two or more excerpts, which score equally high, only the first of them will be retained, and the rest of equally-scoring excerpts will be discarded, in favor of other excerpts (possibly lower scoring).
> To fix this the Set should be replaced with a List + a sort operation. To keep the relative position of excerpts in the original order the Excerpt class should be extended with an "int order" field, and the collected excerpts should be sorted in that order prior to adding them to the summary.

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