#include <enquire.h>
Inheritance diagram for Xapian::BM25Weight:
Public Member Functions | |
BM25Weight (double k1_, double k2_, double k3_, double b_, double min_normlen_) | |
Construct a BM25 weight. | |
BM25Weight * | clone () const |
Return a new weight object of this type. | |
std::string | name () const |
Name of the weighting scheme. | |
std::string | serialise () const |
Serialise object parameters into a string. | |
BM25Weight * | unserialise (const std::string &s) const |
Create object given string serialisation returned by serialise(). | |
Xapian::weight | get_sumpart (Xapian::termcount wdf, Xapian::doclength len) const |
Get a weight which is part of the sum over terms being performed. | |
Xapian::weight | get_maxpart () const |
Gets the maximum value that get_sumpart() may return. | |
Xapian::weight | get_sumextra (Xapian::doclength len) const |
Get an extra weight for a document to add to the sum calculated over the query terms. | |
Xapian::weight | get_maxextra () const |
Gets the maximum value that get_sumextra() may return. | |
bool | get_sumpart_needs_doclength () const |
return false if the weight object doesn't need doclength |
BM25 weighting options : The BM25 formula is
where
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Construct a BM25 weight.
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Return a new weight object of this type. A subclass called FooWeight taking parameters param1 and param2 should implement this as: virtual FooWeight * clone() const { return new FooWeight(param1, param2); } Implements Xapian::Weight. |
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Gets the maximum value that get_sumextra() may return. This is used in optimising searches. Implements Xapian::Weight. |
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Gets the maximum value that get_sumpart() may return. This is used in optimising searches, by having the postlist tree decay appropriately when parts of it can have limited, or no, further effect. Implements Xapian::Weight. |
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Get an extra weight for a document to add to the sum calculated over the query terms. This returns a weight for a given document, and is used by some weighting schemes to account for influence such as document length.
Implements Xapian::Weight. |
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Get a weight which is part of the sum over terms being performed. This returns a weight for a given term and document. These weights are summed to give a total weight for the document.
Implements Xapian::Weight. |
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return false if the weight object doesn't need doclength
Reimplemented from Xapian::Weight. |
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Name of the weighting scheme. If the subclass is called FooWeight, this should return "Foo". Implements Xapian::Weight. |
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Serialise object parameters into a string.
Implements Xapian::Weight. |
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Create object given string serialisation returned by serialise().
Implements Xapian::Weight. |