[Xapian-tickets] [Xapian] #756: Implement dice coefficient weight metric

[Xapian]

#756: Implement dice coefficient weight metric
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 Reporter:  gp1308  |             Owner:  gp1308
     Type:  task    |            Status:  new
 Priority:  normal  |         Milestone:
Component:  Other   |           Version:
 Severity:  normal  |        Resolution:
 Keywords:          |        Blocked By:
 Blocking:          |  Operating System:  All
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Comment (by olly):

 If I follow you want a lower bound on the number of unique terms in any
 document in the collection - we don't track that, but we know `1` is a
 lower bound for it (because documents without any terms wouldn't get
 weighted).

 It's not necessarily a tight bound, but it's the best we can do right now.

 We could certainly start to track bounds on the number of unique terms -
 you could usefully make that a stretch goal of your project (and for older
 databases without that information, we can return 1 for the lower bound
 and the doclength upper bound for the unique terms upper bound).

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Ticket URL: <https://trac.xapian.org/ticket/756#comment:6>
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