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From Ramprakash Ramamoorthy <youngestachie...@gmail.com>
Subject Re: Multiple faceting in lucene
Date Fri, 01 Feb 2013 07:12:19 GMT
On Fri, Jan 25, 2013 at 6:23 PM, Shai Erera <serera@gmail.com> wrote:

> Hi
>
> Are the values of 'a' and 'b' known in advance? Is it a limited set of
> values? Are you always interested in a table which covers all values?
>
> If so, one way to do that is to each value of 'a' against all values of
> 'b'. Of course, pick as pivot the dimension with the least values. Note
> however that if the number of values of 'a' and 'b' are big, it may be
> costly to run N searches (even if you optimize the query processing).
>
> If the cardinality of 'a' and 'b' is small, and if you index for each
> document only one value of 'a' and one value of 'b' (maybe some documents
> only have 'a' or 'b'...), then there is another way.
> You can run the query 'a AND b', where 'a' and 'b' are the facet dimensions
> and for every matching document count a "fake" facet which is a pair of
> ordinals, e.g. [1,45], [1,23] ...
> In the end, you'll have the counts of the pair of ordinals and you can use
> TaxonomyReader to label the ordinals of each pair and return the table.
> That will work as long as the cardinality of 'a' and 'b' is sane :-)
>
> Shai
>
> Thank you Shai, I was able to achieve it roundabout. I read this blog<http://shaierera.blogspot.com/2012/12/lucene-facets-under-hood.html>of
yours  and came to know about the setDepth method in FacetRequest. Was
able to solve my use case with it. Thank you for the blog and the answer!

>
> On Fri, Jan 25, 2013 at 12:12 PM, Ramprakash Ramamoorthy <
> youngestachiever@gmail.com> wrote:
>
> > Hello,
> >
> >         After reading the facet help document of Lucene 4, I can see it
> > helps for a folder structure like faceting. I would like to have a
> > multi-level/multiple faceting in my application.
> >
> >         Let me explain, we have a requirement of something like a
> > contingency table
> > (wikipedia<http://en.wikipedia.org/wiki/Contingency_table> link).
> > Say we are having two fields a and b, I need to know the facet counts of
> b,
> > for each distinct value in a. Also apart from contingency matrix, this
> > could expand to more than 2 fields as well.
> >
> >         Is there a way/work around lucene can help me with such multi
> level
> > faceting. Please advice. Thanks in advance.
> >
> > --
> > With Thanks and Regards,
> > Ramprakash Ramamoorthy,
> > India.
> >
>



-- 
With Thanks and Regards,
Ramprakash Ramamoorthy,
India,
+91 9626975420

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