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 On Fri, Jan 25, 2013 at 12:12 PM, Ramprakash Ramamoorthy < youngestachie...@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. >
