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Message-Id: <s2a01d6e.084@gwia201.syr.edu>
Date: Fri, 03 Jun 2005 09:05:20 -0400
From: "Grant Ingersoll" <GSIngers@syr.edu>
To: <java-user@lucene.apache.org>
Subject: RE: calculate wi = tfi * IDFi for each document.
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If you can, I think there has been enough interest in the past on this,
a patch that exposes the wi information would probably be useful to
others (not that I am saying it would be committed, as I can't speak for
the committers on the project)

>>> andrew.boyd@mindspring.com 6/3/2005 8:19:16 AM >>>
Thanks for the reply.  It looks like I can use parts of Similarity.

I'll post back once I get it working or at least closer ;-)

Andrew

-----Original Message-----
From: Grant Ingersoll <GSIngers@syr.edu>
Sent: Jun 3, 2005 6:51 AM
To: java-user@lucene.apache.org 
Subject: RE: calculate wi = tfi * IDFi for each document.

I think the TermFreqVector (reader.getTermVector) has the info you
want
per document.  You will need to sort it by frequency to get the top
terms in each document.  It doesn't give you the wi, just tfi, but the
whole score is implied by the fact that you have the top 10 documents,
I
think.

-Grant

>>> andrew.boyd@mindspring.com 6/2/2005 3:21:35 PM >>>
Ok.  So if I get 10 Documents back from a search and I want to get the
top 5 weighted terms for each of the 10 documents what API call should
I
use?  I'm unable to find the connection between Similarity and a
Document.

I know I'm missing the elephant that must be in the middle of the
room.
 Or maybe it's not there.
Is what I'm trying to do do-able?

Thanks,

Andrew

-----Original Message-----
From: Max Pfingsthorn <m.pfingsthorn@hippo.nl>
Sent: Jun 2, 2005 5:33 AM
To: java-user@lucene.apache.org 
Subject: RE: calculate wi = tfi * IDFi for each document.

Hi,

DefaultSimilarity uses exactly this weighting scheme. Makes sense
since
it's a pretty standard relevance measure...

Bye!
max

-----Original Message-----
From: Andrew Boyd [mailto:andrew.boyd@mindspring.com] 
Sent: Thursday, June 02, 2005 11:39
To: java-user@lucene.apache.org 
Subject: calculate wi = tfi * IDFi for each document.


If I have search results how can I calculate, using lucene's API,  wi
=
tfi * IDFi for each document.

wi    = term weight
tfi    = term frequency in a document
IDFi = inverse document frequency = log(D/dfi)
dfi   = document frequency or number of documents containing term i
D    = number of documents in my search result

Thanks,

Andrew

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Andrew Boyd
Software Architect
Sun Certified J2EE Architect
B&B Technical Services Inc.
205.422.2557

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