public class MultiSimilarity extends SimilarityImplements the CombSUM method for combining evidence from multiple similarity values described in: Joseph A. Shaw, Edward A. Fox. In Text REtrieval Conference (1993), pp. 243-252
- WARNING: This API is experimental and might change in incompatible ways in the next release.
All Methods Instance Methods Concrete Methods Modifier and Type Method Description
computeNorm(FieldInvertState state)Computes the normalization value for a field, given the accumulated state of term processing for this field (see
scorer(float boost, CollectionStatistics collectionStats, TermStatistics... termStats)Compute any collection-level weight (e.g.
protected final Similarity simsthe sub-similarities used to create the combined score
public MultiSimilarity(Similarity sims)Creates a MultiSimilarity which will sum the scores of the provided
public long computeNorm(FieldInvertState state)Description copied from class:
SimilarityComputes the normalization value for a field, given the accumulated state of term processing for this field (see
Matches in longer fields are less precise, so implementations of this method usually set smaller values when
state.getLength()is large, and larger values when
Note that for a given term-document frequency, greater unsigned norms must produce scores that are lower or equal, ie. for two encoded norms
Long.compareUnsigned(n1, n2) > 0then
SimScorer.score(freq, n1) <= SimScorer.score(freq, n2)for any legal
0is not a legal norm, so
1is the norm that produces the highest scores.
public Similarity.SimScorer scorer(float boost, CollectionStatistics collectionStats, TermStatistics... termStats)Description copied from class:
SimilarityCompute any collection-level weight (e.g. IDF, average document length, etc) needed for scoring a query.
- Specified by:
boost- a multiplicative factor to apply to the produces scores
collectionStats- collection-level statistics, such as the number of tokens in the collection.
termStats- term-level statistics, such as the document frequency of a term across the collection.
- SimWeight object with the information this Similarity needs to score a query.