[Xapian-tickets] [Xapian] #733: Change the way Features request statistics
Xapian
nobody at xapian.org
Sat Aug 20 09:23:13 BST 2016
#733: Change the way Features request statistics
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Reporter: ayshtmr | Owner: ayshtmr
Type: enhancement | Status: new
Priority: normal | Milestone:
Component: Letor (Learning To Rank) | Version: 1.4.0
Severity: normal | Keywords: Letor features
Blocked By: | Blocking:
Operating System: All |
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At present, `Feature::Internal` class does the work of calculating
statistics like normalised lengths, query term frequencies, etc,.
`Feature` subclasses then request these statistics from `get_value()`
method. Due to presence of Internal member in `Feature` class, subclassing
`Feature` is not easy as well.
The following changes need to be made:
1. `Feature::Internal` should be eliminated and its functionality (i.e.
calculating and supplying statistics to `Feature` subclasses) should be
made part of `FeatureList` class (probably as `FeatureList::Internal`
class). [[br]]
2. It's possible that we could also do the thing `Weight` does, and have
each `Feature` subclass report which statistics it needs, so `FeatureList`
can calculate them each once in advance before calling `get_value()` on
all its `Feature` objects.
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Ticket URL: <https://trac.xapian.org/ticket/733>
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