org.apache.solr.search.similarities
Class DFRSimilarityFactory
java.lang.Object
org.apache.solr.schema.SimilarityFactory
org.apache.solr.search.similarities.DFRSimilarityFactory
public class DFRSimilarityFactory
- extends SimilarityFactory
Factory for DFRSimilarity
You must specify the implementations for all three components of
DFR (strings). In general the models are parameter-free, but two of the
normalizations take floating point parameters (see below):
basicModel
: Basic model of information content:
Be
: Limiting form of Bose-Einstein
G
: Geometric approximation of Bose-Einstein
P
: Poisson approximation of the Binomial
D
: Divergence approximation of the Binomial
I(n)
: Inverse document frequency
I(ne)
: Inverse expected document
frequency [mixture of Poisson and IDF]
I(F)
: Inverse term frequency
[approximation of I(ne)]
afterEffect
: First normalization of information
gain:
L
: Laplace's law of succession
B
: Ratio of two Bernoulli processes
none
: no first normalization
normalization
: Second (length) normalization:
H1
: Uniform distribution of term
frequency
- parameter c (float): hyper-parameter that controls
the term frequency normalization with respect to the
document length. The default is
1
H2
: term frequency density inversely
related to length
- parameter c (float): hyper-parameter that controls
the term frequency normalization with respect to the
document length. The default is
1
H3
: term frequency normalization
provided by Dirichlet prior
- parameter mu (float): smoothing parameter μ. The
default is
800
Z
: term frequency normalization provided
by a Zipfian relation
- parameter z (float): represents
A/(A+1)
where A measures the specificity of the language.
The default is 0.3
none
: no second normalization
Optional settings:
- WARNING: This API is experimental and might change in incompatible ways in the next release.
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
DFRSimilarityFactory
public DFRSimilarityFactory()
init
public void init(SolrParams params)
- Overrides:
init
in class SimilarityFactory
getSimilarity
public Similarity getSimilarity()
- Specified by:
getSimilarity
in class SimilarityFactory
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