public class IBSimilarity extends SimilarityBase
The retrieval function is of the form RSV(q, d) = ∑ -xqw log Prob(Xw ≥ tdw | λw), where
The framework described in the paper has many similarities to the DFR
framework (see DFRSimilarity
). It is possible that the two
Similarities will be merged at one point.
To construct an IBSimilarity, you must specify the implementations for all three components of the Information-Based model.
Distribution
: Probabilistic distribution used to
model term occurrence
DistributionLL
: Log-logisticDistributionLL
: Smoothed power-lawLambda
: λw parameter of the
probability distribution
Normalization
: Term frequency normalization
Any supported DFR normalization (listed in
DFRSimilarity
)
DFRSimilarity
Similarity.SimScorer, Similarity.SimWeight
Constructor and Description |
---|
IBSimilarity(Distribution distribution,
Lambda lambda,
Normalization normalization)
Creates IBSimilarity from the three components.
|
Modifier and Type | Method and Description |
---|---|
Distribution |
getDistribution()
Returns the distribution
|
Lambda |
getLambda()
Returns the distribution's lambda parameter
|
Normalization |
getNormalization()
Returns the term frequency normalization
|
String |
toString()
The name of IB methods follow the pattern
IB <distribution> <lambda><normalization> . |
computeNorm, computeWeight, getDiscountOverlaps, log2, setDiscountOverlaps, simScorer
coord, queryNorm
public IBSimilarity(Distribution distribution, Lambda lambda, Normalization normalization)
Note that null
values are not allowed:
if you want no normalization, instead pass
Normalization.NoNormalization
.
distribution
- probabilistic distribution modeling term occurrencelambda
- distribution's λw parameternormalization
- term frequency normalizationpublic String toString()
IB <distribution> <lambda><normalization>
. The name of the
distribution is the same as in the original paper; for the names of lambda
parameters, refer to the javadoc of the Lambda
classes.toString
in class SimilarityBase
public Distribution getDistribution()
public Lambda getLambda()
public Normalization getNormalization()
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