Thank You very much --Tim
> -----Ursprüngliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Auftrag von Chris > Hostetter > Gesendet: Dienstag, 18. Januar 2005 04:56 > An: Lucene Users List > Betreff: Re: How to get all field values from a Hits object? > > > > : is it possible to get all different values for a > : <Field> from a <Hits> object and how to do this? > > The ording of your question suggests that the Field you are > interested in > isn't a field which will have a fairly unique value for every > doc (ie: not > a "title", more likely an "author" or "category" field). > Starting with > that assumption, then there is fairly efficient way to get > the information > you want... > > Assuming the total set of values for the Field you are > interested in is > small (relative your index size), you can pre-compute a BitSet for > each value indicating which docs match that value in the > Field (using a > TermFilter). Then store those BitSets in a Map (key'ed by > field value) > > Everytime a search is performed, use a HitCollector that generates a > BitSet containing the documents in your result; AND that > BitSet against (a > copy of) each BitSet in your Map. All of the resulting BitSets with a > non-zero cardinality represent values in your results. (As > an added bonus > the cardinality() of each BitSet is the total number of docs in your > result that contain that value) > > Two caveats: > 1) Everytime you modify your index, you have to regen the > BitSets in your Map. > 2) You have to know the set of all values for the field you are > interested in. In many cases, this is easy to > determine from the > source data while building the index. but it's also possible to > get it using IndexReader.termDocs(Term). > > > (I'm doing something like this to provide ancilary > information about which > categories of documents are most common in the users search > result, and > what the exact number of documents in those categories is) > > > -Hoss > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
