Xapian discuss - Mar 2005 - Modifying Result Relevance

Hi, I'm running Xapian 0.8.3 via PHP. I've been running it successfully
for
several months and it currently indexes 180,000 documents in one collection
and 67,000 in another.

My client has decided that he wants to give the highest relevance to
documents that contain the highest number of search terms, with no regard
for the document length or other factors. I don't really like that approach
but I do my best to keep them happy. Is there any way to accomplish this
search result scenario with Xapian? Perhaps with the weighting stuff, but I
seem to recall that it wasn't accessible from the PHP interface...is that
correct?

Thanks,
Mike.

(P.S. I've been reluctant to upgrade Xapian with all the PHP/SWIG discussion
going on...is it safe yet?)

On Tue, Mar 29, 2005 at 09:17:57AM -0500, Mike Boone
wrote:
> My client has decided that he wants to give the highest relevance to
> documents that contain the highest number of search terms, with no regard
> for the document length or other factors. I don't really like that
approach
> but I do my best to keep them happy. Is there any way to accomplish this
> search result scenario with Xapian?
This is what you'll get from BM25 with large k1 and k2=0, k3=0, b=0.
In the TREC tests, "large k1" is usually 10000.
> Perhaps with the weighting stuff, but I seem to recall that it wasn't
> accessible from the PHP interface...is that correct?
You can't derive your own subclass of Xapian::Weight in PHP, but I
believe you can create a BM25Weight object and tell Enquire to use it.
If not, it shouldn't be hard to make that work.
> (P.S. I've been reluctant to upgrade Xapian with all the PHP/SWIG
discussion
> going on...is it safe yet?)
That's all in CVS HEAD.  The released versions should work (but use
xapian-bindings 0.8.5.1 rather than 0.8.5).

Cheers,
    Olly