As best I understand it, you DO NOT WANT A FILTER. Filters do notcontribute to scoring, therefore do not rank your documents. If you use a filter, the most irrelevant document could be first. You want to use a HitCollector, see the link in my last e-mail. That link includes an example of using a bitset, which you can create pretty easily from your list of document IDs.
Best Erick On Mon, May 18, 2009 at 2:55 AM, liat oren <oren.l...@gmail.com> wrote: > Sorry I didn't explain myself well. > > The problem I try to address is the following: > Think about the case where you have 100,000 documents indexed. Take word > 'a' > - if it appears in 80,000 documents, you want the score to take it into > account. You want only to see how 20,000 documents are close to a query, > and > only 10,000 of these contain the word 'a'. > 80,000 / 100,000 (the 'statistics' of the whole index) is much smaller than > 10,000 / 20,000 (the 'statistics of only the group of documents). So it > does > affect the score if I use the whole index or just the documents I am > interested in. > It might be that the order of these desired documents will not change, but > I > don;t see how you can assure it since the idf value can be really > different. > > So, I want the documents for my query to be > ranked *relative to each other*, AND NOT restricted to only the documents > I care about. > For that case, I need to use the filter, right? > > Its fine if I get the results in DocumentID - then I open these using > IndexReader to get the fields I need. > > Could you please give me an example of how I creat the Filter that filters > out a given list of ids? > > Thanks! > Liat > 2009/5/18 Erick Erickson <erickerick...@gmail.com> > > > I'm still unclear what you want the statistics *for*. "statistics" > > are pretty meaningless as far as I understand. The whole point > > of scoring is to use various "statistics" to *rank* documents *for > > a specific query*. You cannot, for instance, compare scores > > between different queries in any meaningful way. > > > > If you're saying that you want the documents for your query to be > > ranked *relative to each other*, but restricted to only the documents > > you care about, then I think you need a HitCollector > > because a Filter (last I knew) doesn't score documents therefore > > won't order them. > > > > But asking if the statistics reflect the whole index just isn't making > any > > sense to me. If you're asking that question I suspect that there's > > something about your problem space I don't understand and > > you're not explaining simply enough for me to grasp <G>. > > > > So forget a Filter because you'll get the documents back in > > (probably, but my memory is weak some days) document ID > > order. Implement a HitCollector whose collect method only > > sets bits for docs in your list. See: > > > > > http://lucene.apache.org/java/2_2_0/api/org/apache/lucene/search/HitCollector.html#collect(int,%20float) > > > > Best > > Erick > > > > > > On Sun, May 17, 2009 at 3:57 AM, liat oren <oren.l...@gmail.com> wrote: > > > > > Yes, this is what I need - I don't need to get the scores for the > > documents > > > that were filtered. > > > The statistics I ment are idf(t) for example. > > > I want these to include the whole index of course. > > > It will include this info of all the index, right? > > > > > > if I have a list of ids that the query should look at, which Filter > > should > > > I > > > use? > > > > > > Thanks a lot, > > > Liat > > > > > > 2009/5/14 Erick Erickson <erickerick...@gmail.com> > > > > > > > Hmmm, come to think of it, if you pass the Filter to the search > > I*think* > > > > you > > > > don't get scores for that clause, but you may want to > > > > check it out... > > > > > > > > So I think you should think about implementing a HitCollector > > > > and collect only the documents you care about. > > > > > > > > This is really very little extra work since all the documents have > > > > to be evaluated anyway. > > > > > > > > I'm not sure what you mean by statistics for the whole index. I > suspect > > > > you're wondering if the scores reflect all the documents. But you > don't > > > > care because scores are not relevant between different queries, and > > > > if they are calculated only within the query you're running, all the > > > > documents returned have scores that rank them relative to each other. > > > > > > > > Best > > > > Erick > > > > > > > > On Thu, May 14, 2009 at 9:16 AM, liat oren <oren.l...@gmail.com> > > wrote: > > > > > > > > > Yes, I have a pre-defined list of documents that I care about. > > > > > Then I can do the search on these, but it will take the statictics > of > > > the > > > > > whole index, right? > > > > > > > > > > > > > > > > > > > > > > > > > 2009/5/14 Erick Erickson <erickerick...@gmail.com> > > > > > > > > > > > I don't know if I'm understanding what you want, but if you havea > > > > > > pre-defined list of documents, couldn't you form a Filter? Then > > > > > > your results would only be the documents you care about. > > > > > > > > > > > > If this is irrelevant, perhaps you could explain a bit more about > > > > > > the problem you're trying to solve. > > > > > > > > > > > > Best > > > > > > Erick > > > > > > > > > > > > On Thu, May 14, 2009 at 5:03 AM, liat oren <oren.l...@gmail.com> > > > > wrote: > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > I have a big index and I want to get for a specific search only > > the > > > > > > grades > > > > > > > of a list of documents. > > > > > > > Is there a better way to get this score than looping on all the > > > > > reasults > > > > > > > set? > > > > > > > > > > > > > > Thanks, > > > > > > > Liat > > > > > > > > > > > > > > > > > > > > > > > > > > > >
