Thanks for bearing with me Max.
I do understand that the hits come back sorted by decending score after their
Similarity has been computed relative to the query vector. What I was hoping
to do was use the built in fuctionality of lucene to calculate some term
weights specifically wi = ti * IDFi.
Assuming I had Hits I was <b>hoping</b> to do something like this:
for(int idx = 0; idx < hits.lingth(); idx++){
int id = hits.id(idx);
TermFreqVector[] termFreqVec = indexReader.getTermFreqVectors(id);
// Using the termFreqVec calculate the wi for each term in that document.
for(termFreqVec){
TermWeight wi = Similarity.wi(termFreqVec[], termFreqVec.length);
...
}
}
Andrew
-----Original Message-----
From: Max Pfingsthorn <[EMAIL PROTECTED]>
Sent: Jun 3, 2005 4:13 AM
To: java-user@lucene.apache.org
Subject: RE: calculate wi = tfi * IDFi for each document.
Hi,
when IndexSearcher.search gives you a Hits object back, all results are already
sorted by their score, which is computed internally using the Similarity. You
can access it via Hits.score(n) (see
http://lucene.apache.org/java/docs/api/org/apache/lucene/search/Hits.html).
This is also shown in the demo in org.apache.lucene.demo.SearchFiles from SVN.
(see
http://svn.apache.org/viewcvs.cgi/lucene/java/trunk/src/demo/org/apache/lucene/demo/SearchFiles.java?rev=150739&view=markup).
Hope that helps.
max
-----Original Message-----
From: Andrew Boyd [mailto:[EMAIL PROTECTED]
Sent: Thursday, June 02, 2005 21:22
To: java-user@lucene.apache.org
Subject: RE: calculate wi = tfi * IDFi for each document.
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 <[EMAIL PROTECTED]>
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:[EMAIL PROTECTED]
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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Software Architect
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B&B Technical Services Inc.
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