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Nov 20, 2009, 6:59 PM
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[jira] Issue Comment Edited: (LUCENE-1360) A Similarity class which has unique length norms for numTerms <= 10
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[ https://issues.apache.org/jira/browse/LUCENE-1360?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12780897#action_12780897 ]
Lance Norskog edited comment on LUCENE-1360 at 11/21/09 2:58 AM:
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This is a graph of the standard norms against the results of this patch. The orange/red dots at the left are the elevated values for boosting short documents.
Both displays show the norms after the 8-bit encode/decode process, rather than raw 1/x. Here is the code for the generator:
{code}
public class FloatEncode {
private static float ARR[] = { 0.0f, 1.5f, 1.25f, 1.0f, 0.875f, 0.75f,
0.625f, 0.5f, 0.4375f, 0.375f, 0.3125f};
public static void main(String[] args) {
for(int i = 1; i < 100; i++) {
float f = i;
f = 1/f;
byte b = SmallFloat.floatToByte315(f);
float f2 = SmallFloat.byte315ToFloat(b);
float ff = f2;
if (i < ARR.length)
ff = ARR[i];
System.out.println(i + "," + f2 + "," + ff);
}
}
}
{code}
was (Author: lancenorskog):
This is a graph of the standard norms against the results of this patch. The orange/red dots at the left are the elevated values for boosting short documents.
Both displays show the norms after the 8-bit encode/decode process, rather than raw 1/x. Here is the code for the generator:
public class FloatEncode {
private static float ARR[] = { 0.0f, 1.5f, 1.25f, 1.0f, 0.875f, 0.75f, 0.625f, 0.5f, 0.4375f, 0.375f, 0.3125f};
/**
* @param args
*/
public static void main(String[] args) {
for(int i = 1; i < 100; i++) {
float f = i;
f = 1/f;
byte b = SmallFloat.floatToByte315(f);
float f2 = SmallFloat.byte315ToFloat(b);
float ff = f2;
if (i < ARR.length)
ff = ARR[i];
System.out.println(i + "," + f2 + "," + ff);
}
}
}
> A Similarity class which has unique length norms for numTerms <= 10
> -------------------------------------------------------------------
>
> Key: LUCENE-1360
> URL: https://issues.apache.org/jira/browse/LUCENE-1360
> Project: Lucene - Java
> Issue Type: Improvement
> Reporter: Sean Timm
> Assignee: Otis Gospodnetic
> Priority: Trivial
> Attachments: LUCENE-1380 visualization.pdf, ShortFieldNormSimilarity.java
>
>
> A Similarity class which extends DefaultSimilarity and simply overrides lengthNorm. lengthNorm is implemented as a lookup for numTerms <= 10, else as {{1/sqrt(numTerms)}}. This is to avoid term counts below 11 from having the same lengthNorm after stored as a single byte in the index.
> This is useful if your search is only on short fields such as titles or product descriptions.
> See mailing list discussion: http://www.nabble.com/How-to-boost-the-score-higher-in-case-user-query-matches-entire-field-value-than-just-some-words-within-a-field-td19079221.html
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