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From Doug Cutting <cutt...@apache.org>
Subject Re: Scoring without normalization!
Date Thu, 15 Jul 2004 17:19:51 GMT
Have you looked at:

http://jakarta.apache.org/lucene/docs/api/org/apache/lucene/search/Similarity.html

in particular, at:

http://jakarta.apache.org/lucene/docs/api/org/apache/lucene/search/Similarity.html#lengthNorm(java.lang.String,%20int)
http://jakarta.apache.org/lucene/docs/api/org/apache/lucene/search/Similarity.html#queryNorm(float)

Doug

Jones G wrote:
> Sadly, I am still running into problems
> 
> Explain shows the following after the modification.
> 
> Rank: 1     ID: 11285358    Score: 5.5740864E8
> 5.5740864E8 = product of:
>   8.3611296E8 = sum of:
>     8.3611296E8 = product of:
>       6.6889037E9 = weight(title:iron in 1235940), product of:
>         0.12621856 = queryWeight(title:iron), product of:
>           7.0507255 = idf(docFreq=10816)
>           0.017901499 = queryNorm
>         5.2994613E10 = fieldWeight(title:iron in 1235940), product of:
>           1.0 = tf(termFreq(title:iron)=1)
>           7.0507255 = idf(docFreq=10816)
>           7.5161928E9 = fieldNorm(field=title, doc=1235940)
>       0.125 = coord(1/8)
>     2.7106019E-8 = product of:
>       1.08424075E-7 = sum of:
>         5.7318403E-9 = weight(abstract:an in 1235940), product of:
>           0.03711049 = queryWeight(abstract:an), product of:
>             2.073038 = idf(docFreq=1569960)
>             0.017901499 = queryNorm
>           1.5445337E-7 = fieldWeight(abstract:an in 1235940), product of:
>             1.0 = tf(termFreq(abstract:an)=1)
>             2.073038 = idf(docFreq=1569960)
>             7.4505806E-8 = fieldNorm(field=abstract, doc=1235940)
>         1.0269223E-7 = weight(abstract:iron in 1235940), product of:
>           0.111071706 = queryWeight(abstract:iron), product of:
>             6.2046037 = idf(docFreq=25209)
>             0.017901499 = queryNorm
>           9.24558E-7 = fieldWeight(abstract:iron in 1235940), product of:
>             2.0 = tf(termFreq(abstract:iron)=4)
>             6.2046037 = idf(docFreq=25209)
>             7.4505806E-8 = fieldNorm(field=abstract, doc=1235940)
>       0.25 = coord(2/8)
>   0.6666667 = coord(2/3)
> Rank: 2     ID: 8157438     Score: 2.7870432E8
> 2.7870432E8 = product of:
>   8.3611296E8 = product of:
>     6.6889037E9 = weight(title:iron in 159395), product of:
>       0.12621856 = queryWeight(title:iron), product of:
>         7.0507255 = idf(docFreq=10816)
>         0.017901499 = queryNorm
>       5.2994613E10 = fieldWeight(title:iron in 159395), product of:
>         1.0 = tf(termFreq(title:iron)=1)
>         7.0507255 = idf(docFreq=10816)
>         7.5161928E9 = fieldNorm(field=title, doc=159395)
>     0.125 = coord(1/8)
>   0.33333334 = coord(1/3)
> Rank: 3     ID: 10543103    Score: 2.7870432E8
> 2.7870432E8 = product of:
>   8.3611296E8 = product of:
>     6.6889037E9 = weight(title:iron in 553967), product of:
>       0.12621856 = queryWeight(title:iron), product of:
>         7.0507255 = idf(docFreq=10816)
>         0.017901499 = queryNorm
>       5.2994613E10 = fieldWeight(title:iron in 553967), product of:
>         1.0 = tf(termFreq(title:iron)=1)
>         7.0507255 = idf(docFreq=10816)
>         7.5161928E9 = fieldNorm(field=title, doc=553967)
>     0.125 = coord(1/8)
>   0.33333334 = coord(1/3)
> Rank: 4     ID: 8753559     Score: 2.7870432E8
> 2.7870432E8 = product of:
>   8.3611296E8 = product of:
>     6.6889037E9 = weight(title:iron in 2563152), product of:
>       0.12621856 = queryWeight(title:iron), product of:
>         7.0507255 = idf(docFreq=10816)
>         0.017901499 = queryNorm
>       5.2994613E10 = fieldWeight(title:iron in 2563152), product of:
>         1.0 = tf(termFreq(title:iron)=1)
>         7.0507255 = idf(docFreq=10816)
>         7.5161928E9 = fieldNorm(field=title, doc=2563152)
>     0.125 = coord(1/8)
>   0.33333334 = coord(1/3)
> 
> I would like to get rid of all normalizations and just have TF and IDF.
> What am I missing?
> 
> 
> On Thu, 15 Jul 2004 Anson Lau wrote :
> 
>>If you don't mind hacking the source:
>>
>>In Hits.java
>>
>>In method "getMoreDocs()"
>>
>>
>>
>>    // Comment out the following
>>    //float scoreNorm = 1.0f;
>>    //if (length > 0 && scoreDocs[0].score > 1.0f) {
>>    //  scoreNorm = 1.0f / scoreDocs[0].score;
>>    //}
>>
>>    // And just set scoreNorm to 1.
>>    int scoreNorm = 1;
>>
>>
>>I don't know if u can do it without going to the src.
>>
>>Anson
>>
>>
>>-----Original Message-----
>>From: Jones G [mailto:jones.g@rediffmail.com]
>>Sent: Thursday, July 15, 2004 6:52 AM
>>To: lucene-user@jakarta.apache.org
>>Subject: Scoring without normalization!
>>
>>How do I remove document normalization from scoring in Lucene? I just want
>>to stick to TF IDF.
>>
>>Thanks.
>>
>>
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> 
> 

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