Question about scoring normalisation

[Karl Koch <Th...@gmx.net>]

Hello all,

I am wondering how many of you actually work with own scoring mechanism
(overwriting Lucenes standard scoring) and how many of you do work on how to
normalise this score. 

I would like to add a second score on top of Lucenes TF/IDF score. The
resulting score is most likely higher then 1.0. However, the score should be
between 0.0 and 1.0. What is the best way to do that? If Lucene is
normalising its score (if no boosting is applied) to a maximium of 1.0, how
is this done (in Lucene 1.2 and/or beyond) ?

Regards,
Karl


-- 
Highspeed-Freiheit. Bei GMX superg�nstig, z.B. GMX DSL_Cityflat,
DSL-Flatrate f�r nur 4,99 Euro/Monat*  http://www.gmx.net/de/go/dsl

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Re: Question about scoring normalisation

[Yonik Seeley <ys...@gmail.com>]

On 11/5/05, Sameer Shisodia <ge...@gmail.com> wrote:
> if so the top score should always be 1.0. Isn't so.
> Or does boosting multiple individual fields wreck that ?
> sameer

The top score is scaled back to 1.0 *only* if it's greater than 1.0

So hits with scores of 4.0,2.0 will be normalized to 1.0,0.5
while hits of 0.4,0.2 will be normalized to 0.4,0.2

-Yonik

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Re: Question about scoring normalisation

[Otis Gospodnetic <ot...@yahoo.com>]

> if so the top score should always be 1.0. Isn't so.

Perhaps you are right.  Can you send some code that shows this,
preferably writen as a JUnit test and attached to a JIRA issues?

> Or does boosting multiple individual fields wreck that ?

I didn't think so, but I could be wrong.

Otis

> sameer
> 
> On 11/6/05, Chris Lamprecht <cl...@gmail.com> wrote:
> > Lucene just takes the highest score returned, and divides all
> scores
> > by this max_score.  So max_score / max_score = 1.0, and voila.
> >
> >
> --
> Sameer Shisodia  Bangalore
> 
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> 


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Re: Question about scoring normalisation

[Sameer Shisodia <ge...@gmail.com>]

if so the top score should always be 1.0. Isn't so.
Or does boosting multiple individual fields wreck that ?
sameer

On 11/6/05, Chris Lamprecht <cl...@gmail.com> wrote:
> Lucene just takes the highest score returned, and divides all scores
> by this max_score.  So max_score / max_score = 1.0, and voila.
>
>
--
Sameer Shisodia  Bangalore

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Re: Question about scoring normalisation

[Chris Lamprecht <cl...@gmail.com>]

Lucene just takes the highest score returned, and divides all scores
by this max_score.  So max_score / max_score = 1.0, and voila.

On 11/5/05, Karl Koch <Th...@gmx.net> wrote:
> Hello all,
>
> I am wondering how many of you actually work with own scoring mechanism
> (overwriting Lucenes standard scoring) and how many of you do work on how to
> normalise this score.
>
> I would like to add a second score on top of Lucenes TF/IDF score. The
> resulting score is most likely higher then 1.0. However, the score should be
> between 0.0 and 1.0. What is the best way to do that? If Lucene is
> normalising its score (if no boosting is applied) to a maximium of 1.0, how
> is this done (in Lucene 1.2 and/or beyond) ?
>
> Regards,
> Karl
>
>
> --
> Highspeed-Freiheit. Bei GMX supergünstig, z.B. GMX DSL_Cityflat,
> DSL-Flatrate für nur 4,99 Euro/Monat*  http://www.gmx.net/de/go/dsl
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-user-help@lucene.apache.org
>
>

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