Lucene.Net
3.0.3
Lucene.Net is a .NET port of the Java Lucene Indexing Library

Expert: Delegating scoring implementation. Useful in Query.GetSimilarity(Searcher) implementations, to override only certain methods of a Searcher's Similiarty implementation.. More...
Inherits Lucene.Net.Search.Similarity.
Inherited by Lucene.Net.Search.BooleanQuery.AnonymousClassSimilarityDelegator, and Lucene.Net.Search.FuzzyLikeThisQuery.FuzzyTermQuery.AnonymousSimilarityDelegator.
Public Member Functions  
SimilarityDelegator (Similarity delegee)  
Construct a Similarity that delegates all methods to another.  
override float  ComputeNorm (System.String fieldName, FieldInvertState state) 
Compute the normalization value for a field, given the accumulated state of term processing for this field (see FieldInvertState).  
override float  LengthNorm (System.String fieldName, int numTerms) 
Computes the normalization value for a field given the total number of terms contained in a field. These values, together with field boosts, are stored in an index and multipled into scores for hits on each field by the search code.  
override float  QueryNorm (float sumOfSquaredWeights) 
Computes the normalization value for a query given the sum of the squared weights of each of the query terms. This value is then multipled into the weight of each query term.  
override float  Tf (float freq) 
Computes a score factor based on a term or phrase's frequency in a document. This value is multiplied by the Idf(int, int) factor for each term in the query and these products are then summed to form the initial score for a document.  
override float  SloppyFreq (int distance) 
Computes the amount of a sloppy phrase match, based on an edit distance. This value is summed for each sloppy phrase match in a document to form the frequency that is passed to Tf(float).  
override float  Idf (int docFreq, int numDocs) 
Computes a score factor based on a term's document frequency (the number of documents which contain the term). This value is multiplied by the Tf(int) factor for each term in the query and these products are then summed to form the initial score for a document.  
override float  Coord (int overlap, int maxOverlap) 
Computes a score factor based on the fraction of all query terms that a document contains. This value is multiplied into scores.  
override float  ScorePayload (int docId, string fieldName, int start, int end, byte[] payload, int offset, int length) 
Public Member Functions inherited from Lucene.Net.Search.Similarity  
virtual float  Tf (int freq) 
Computes a score factor based on a term or phrase's frequency in a document. This value is multiplied by the Idf(int, int) factor for each term in the query and these products are then summed to form the initial score for a document.  
virtual IDFExplanation  IdfExplain (Term term, Searcher searcher) 
Computes a score factor for a simple term and returns an explanation for that score factor.  
virtual IDFExplanation  IdfExplain (ICollection< Term > terms, Searcher searcher) 
Computes a score factor for a phrase.  
virtual float  ScorePayload (int docId, System.String fieldName, int start, int end, byte[] payload, int offset, int length) 
Calculate a scoring factor based on the data in the payload. Overriding implementations are responsible for interpreting what is in the payload. Lucene makes no assumptions about what is in the byte array. The default implementation returns 1.  
Additional Inherited Members  
Static Public Member Functions inherited from Lucene.Net.Search.Similarity  
static float  DecodeNorm (byte b) 
Decodes a normalization factor stored in an index.  
static float[]  GetNormDecoder () 
Returns a table for decoding normalization bytes.  
static byte  EncodeNorm (float f) 
Encodes a normalization factor for storage in an index.  
Public Attributes inherited from Lucene.Net.Search.Similarity  
const int  NO_DOC_ID_PROVIDED =  1 
Protected Member Functions inherited from Lucene.Net.Search.Similarity  
Similarity ()  
Properties inherited from Lucene.Net.Search.Similarity  
static Similarity  Default [get, set] 
Gets or sets the default Similarity implementation used by indexing and search code. This is initially an instance of DefaultSimilarity.  
Expert: Delegating scoring implementation. Useful in Query.GetSimilarity(Searcher) implementations, to override only certain methods of a Searcher's Similiarty implementation..
Definition at line 29 of file SimilarityDelegator.cs.
Lucene.Net.Search.SimilarityDelegator.SimilarityDelegator  (  Similarity  delegee  ) 
Construct a Similarity that delegates all methods to another.
delegee  the Similarity implementation to delegate to 
Definition at line 35 of file SimilarityDelegator.cs.

virtual 
Compute the normalization value for a field, given the accumulated state of term processing for this field (see FieldInvertState).
Implementations should calculate a float value based on the field state and then return that value.
For backward compatibility this method by default calls LengthNorm(String, int) passing FieldInvertState.Length as the second argument, and then multiplies this value by FieldInvertState.Boost.
WARNING: This API is new and experimental and may suddenly change.
field  field name 
state  current processing state for this field 
Reimplemented from Lucene.Net.Search.Similarity.
Definition at line 40 of file SimilarityDelegator.cs.

virtual 
Computes a score factor based on the fraction of all query terms that a document contains. This value is multiplied into scores.
The presence of a large portion of the query terms indicates a better match with the query, so implementations of this method usually return larger values when the ratio between these parameters is large and smaller values when the ratio between them is small.
overlap  the number of query terms matched in the document 
maxOverlap  the total number of terms in the query 
Implements Lucene.Net.Search.Similarity.
Definition at line 70 of file SimilarityDelegator.cs.

virtual 
Computes a score factor based on a term's document frequency (the number of documents which contain the term). This value is multiplied by the Tf(int) factor for each term in the query and these products are then summed to form the initial score for a document.
Terms that occur in fewer documents are better indicators of topic, so implementations of this method usually return larger values for rare terms, and smaller values for common terms.
docFreq  the number of documents which contain the term 
numDocs  the total number of documents in the collection 
Implements Lucene.Net.Search.Similarity.
Definition at line 65 of file SimilarityDelegator.cs.

virtual 
Computes the normalization value for a field given the total number of terms contained in a field. These values, together with field boosts, are stored in an index and multipled into scores for hits on each field by the search code.
Matches in longer fields are less precise, so implementations of this method usually return smaller values when numTokens
is large, and larger values when numTokens
is small.
Note that the return values are computed under Lucene.Net.Index.IndexWriter.AddDocument(Lucene.Net.Documents.Document) and then stored using EncodeNorm(float). Thus they have limited precision, and documents must be reindexed if this method is altered.
fieldName  the name of the field 
numTokens  the total number of tokens contained in fields named fieldName of doc. 
a normalization factor for hits on this field of this document
Implements Lucene.Net.Search.Similarity.
Definition at line 45 of file SimilarityDelegator.cs.

virtual 
Computes the normalization value for a query given the sum of the squared weights of each of the query terms. This value is then multipled into the weight of each query term.
This does not affect ranking, but rather just attempts to make scores from different queries comparable.
sumOfSquaredWeights  the sum of the squares of query term weights 
Implements Lucene.Net.Search.Similarity.
Definition at line 50 of file SimilarityDelegator.cs.
override float Lucene.Net.Search.SimilarityDelegator.ScorePayload  (  int  docId, 
string  fieldName,  
int  start,  
int  end,  
byte[]  payload,  
int  offset,  
int  length  
) 
Definition at line 75 of file SimilarityDelegator.cs.

virtual 
Computes the amount of a sloppy phrase match, based on an edit distance. This value is summed for each sloppy phrase match in a document to form the frequency that is passed to Tf(float).
A phrase match with a small edit distance to a document passage more closely matches the document, so implementations of this method usually return larger values when the edit distance is small and smaller values when it is large.
distance  the edit distance of this sloppy phrase match 
Implements Lucene.Net.Search.Similarity.
Definition at line 60 of file SimilarityDelegator.cs.

virtual 
Computes a score factor based on a term or phrase's frequency in a document. This value is multiplied by the Idf(int, int) factor for each term in the query and these products are then summed to form the initial score for a document.
Terms and phrases repeated in a document indicate the topic of the document, so implementations of this method usually return larger values when freq
is large, and smaller values when freq
is small.
freq  the frequency of a term within a document 
Implements Lucene.Net.Search.Similarity.
Definition at line 55 of file SimilarityDelegator.cs.