Re: Scoring without normalization!

Thu, 15 Jul 2004 10:20:54 -0700 

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:[EMAIL PROTECTED]
Sent: Thursday, July 15, 2004 6:52 AM
To: [EMAIL PROTECTED]
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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