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Subject: RE: categorisation
Date: Fri, 9 Feb 2007 10:40:30 -0000
Message-ID: <BC1CFC544422CB4A934908E126A4742705BD08E3@SGBLOW2101.wsatkins.com>
Thread-Topic: categorisation
Thread-Index: AcdLsGOblrUbnvD6TPy0Ax86EDMfsgAhkAPg
References: <BC1CFC544422CB4A934908E126A4742705B9BDDF@SGBLOW2101.wsatkins.com>
 <58D0497D-3CC2-4947-96D6-1D7ADE08828F@ehatchersolutions.com>
From: "Kainth, Sachin" <Sachin.Kainth@atkinsglobal.com>
To: <java-user@lucene.apache.org>

It makes sense to me only if you tell me that all the bits in the BitSet
"all" will be 1.=20

-----Original Message-----
From: Erik Hatcher [mailto:erik@ehatchersolutions.com]=20
Sent: 08 February 2007 18:37
To: java-user@lucene.apache.org
Subject: Re: categorisation


On Feb 8, 2007, at 12:36 PM, Kainth, Sachin wrote:

> Chris has given an example of how to perform categorisation of lucene=20
> searches:
>
> String[] mfgs =3D ...;
>   String query =3D "+category:cameras +price:[0 to 10]";
>   Query q =3D QueryParser.parse(query);
>   Hits results =3D searcher.search(q, mySort)
>   BitSet all =3D (new QueryFilter(q)).bits(reader)
>   int[] mfg_counts =3D new int[mfgs.length];
>   for i in (0 to mfgs.length) {
>      BitSet these =3D (new QueryFilter(new TermQuery("mfg",mfgs=20
> [i]))).bits(reader);
>      these.and(all)
>      mfg_counts[i] =3D these.cardinality();
>   }
>
> What I don't understand though is what this line does:
>
> BitSet all =3D (new QueryFilter(q)).bits(reader)
>
> Anyone have any ideas?

"all" is a BitSet lit up for the documents that matched "query".=20=20=20
"these" (the BitSet for a particular category) is .anded with "all"=20=20
to get the counts _left over_ for each category given "query".

Make sense?

	Erik


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