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From Steven Rowe <sar...@syr.edu>
Subject Re: question on setting boost factor
Date Thu, 01 Jul 2004 16:22:20 GMT
Repaired URL (was extra space before "Similarity.html"):
<http://jakarta.apache.org/lucene/docs/api/org/apache/lucene/search/Similarity.html#coord(int,%20int)>

Corresponding Tiny URL:
<URL:http://tinyurl.com/3bo8y>

Erik Hatcher wrote:
> On Jun 22, 2004, at 7:30 AM, Anson Lau wrote:
>> Hi guys,
>>
>> Lets say I want to search the term "hello world" over 3 fields with
>> different boost:
>>
>> ((hello:field1 world:field1)^0.001 (hello:field2 world:field2)^100
>> (hello:field3 world:field3)^20000))
>>
>> Note I've given field1 a really low boost, a heavy boost to field2 and  a
>> REALLY heavy boost to field3.
>>
>> What is happening to me is that a term that matches both field1 and  
>> field2,
>> will have a higher score than a term that matches field3 only, even  
>> though
>> field3's boost is WAY higher.
>>
>> Can I change this behaviour such that the match in field3 only will  
>> actually
>> have a higher score because of the boost?
> 
> 
> First step is to get familiar with the actual factors coming out in the  
> IndexSearcher.explain() output (just System.out.println the Explanation  
> object).  The coord() factor -  
> <http://jakarta.apache.org/lucene/docs/api/org/apache/lucene/search/ 
> Similarity.html#coord(int,%20int)> - is what you'll want to tweak to  
> change how scores are affected when multiple terms match by creating  
> your own DefaultSimilarity sublass (and probably just returning 1.0).   
> Read the javadocs for Similarity to see how to hook in your own  
> implementation (see also section).
> 
>     Erik
> 
> 
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