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| <h1 id="Lucene_Net_Search_Similarities_Similarity" data-uid="Lucene.Net.Search.Similarities.Similarity" class="text-break">Class Similarity |
| </h1> |
| <div class="markdown level0 summary"><p>Similarity defines the components of Lucene scoring. |
| <p> |
| Expert: Scoring API. |
| <p> |
| This is a low-level API, you should only extend this API if you want to implement |
| an information retrieval <em>model</em>. If you are instead looking for a convenient way |
| to alter Lucene's scoring, consider extending a higher-level implementation |
| such as <a class="xref" href="Lucene.Net.Search.Similarities.TFIDFSimilarity.html">TFIDFSimilarity</a>, which implements the vector space model with this API, or |
| just tweaking the default implementation: <a class="xref" href="Lucene.Net.Search.Similarities.DefaultSimilarity.html">DefaultSimilarity</a>. |
| <p> |
| Similarity determines how Lucene weights terms, and Lucene interacts with |
| this class at both <a href="#indextime">index-time</a> and |
| <a href="#querytime">query-time</a>. |
| <p> |
| <a name="indextime"></a> |
| At indexing time, the indexer calls <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html#Lucene_Net_Search_Similarities_Similarity_ComputeNorm_Lucene_Net_Index_FieldInvertState_">ComputeNorm(FieldInvertState)</a>, allowing |
| the <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html">Similarity</a> implementation to set a per-document value for the field that will |
| be later accessible via <a class="xref" href="Lucene.Net.Index.AtomicReader.html#Lucene_Net_Index_AtomicReader_GetNormValues_System_String_">GetNormValues(String)</a>. Lucene makes no assumption |
| about what is in this norm, but it is most useful for encoding length normalization |
| information. |
| <p> |
| Implementations should carefully consider how the normalization is encoded: while |
| Lucene's classical <a class="xref" href="Lucene.Net.Search.Similarities.TFIDFSimilarity.html">TFIDFSimilarity</a> encodes a combination of index-time boost |
| and length normalization information with <a class="xref" href="Lucene.Net.Util.SmallSingle.html">SmallSingle</a> into a single byte, this |
| might not be suitable for all purposes. |
| <p> |
| Many formulas require the use of average document length, which can be computed via a |
| combination of <a class="xref" href="Lucene.Net.Search.CollectionStatistics.html#Lucene_Net_Search_CollectionStatistics_SumTotalTermFreq">SumTotalTermFreq</a> and |
| <a class="xref" href="Lucene.Net.Search.CollectionStatistics.html#Lucene_Net_Search_CollectionStatistics_MaxDoc">MaxDoc</a> or <a class="xref" href="Lucene.Net.Search.CollectionStatistics.html#Lucene_Net_Search_CollectionStatistics_DocCount">DocCount</a>, |
| depending upon whether the average should reflect field sparsity. |
| <p> |
| Additional scoring factors can be stored in named |
| <a class="xref" href="Lucene.Net.Documents.NumericDocValuesField.html">NumericDocValuesField</a>s and accessed |
| at query-time with <a class="xref" href="Lucene.Net.Index.AtomicReader.html#Lucene_Net_Index_AtomicReader_GetNumericDocValues_System_String_">GetNumericDocValues(String)</a>. |
| <p> |
| Finally, using index-time boosts (either via folding into the normalization byte or |
| via <a class="xref" href="Lucene.Net.Index.DocValues.html">DocValues</a>), is an inefficient way to boost the scores of different fields if the |
| boost will be the same for every document, instead the Similarity can simply take a constant |
| boost parameter <em>C</em>, and <a class="xref" href="Lucene.Net.Search.Similarities.PerFieldSimilarityWrapper.html">PerFieldSimilarityWrapper</a> can return different |
| instances with different boosts depending upon field name. |
| <p> |
| <a name="querytime"></a> |
| At query-time, Queries interact with the Similarity via these steps: |
| <ol><li>The <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html#Lucene_Net_Search_Similarities_Similarity_ComputeWeight_System_Single_Lucene_Net_Search_CollectionStatistics_Lucene_Net_Search_TermStatistics___">ComputeWeight(Single, CollectionStatistics, TermStatistics[])</a> method is called a single time, |
| allowing the implementation to compute any statistics (such as IDF, average document length, etc) |
| across <em>the entire collection</em>. The <a class="xref" href="Lucene.Net.Search.TermStatistics.html">TermStatistics</a> and <a class="xref" href="Lucene.Net.Search.CollectionStatistics.html">CollectionStatistics</a> passed in |
| already contain all of the raw statistics involved, so a <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html">Similarity</a> can freely use any combination |
| of statistics without causing any additional I/O. Lucene makes no assumption about what is |
| stored in the returned <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html">Similarity.SimWeight</a> object.</li><li>The query normalization process occurs a single time: <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html#Lucene_Net_Search_Similarities_Similarity_SimWeight_GetValueForNormalization">GetValueForNormalization()</a> |
| is called for each query leaf node, <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html#Lucene_Net_Search_Similarities_Similarity_QueryNorm_System_Single_">QueryNorm(Single)</a> is called for the top-level |
| query, and finally <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html#Lucene_Net_Search_Similarities_Similarity_SimWeight_Normalize_System_Single_System_Single_">Normalize(Single, Single)</a> passes down the normalization value |
| and any top-level boosts (e.g. from enclosing <a class="xref" href="Lucene.Net.Search.BooleanQuery.html">BooleanQuery</a>s).</li><li>For each segment in the index, the <a class="xref" href="Lucene.Net.Search.Query.html">Query</a> creates a <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html#Lucene_Net_Search_Similarities_Similarity_GetSimScorer_Lucene_Net_Search_Similarities_Similarity_SimWeight_Lucene_Net_Index_AtomicReaderContext_">GetSimScorer(Similarity.SimWeight, AtomicReaderContext)</a> |
| The GetScore() method is called for each matching document.</li></ol> |
| <p> |
| <a name="explaintime"></a> |
| When <a class="xref" href="Lucene.Net.Search.IndexSearcher.html#Lucene_Net_Search_IndexSearcher_Explain_Lucene_Net_Search_Query_System_Int32_">Explain(Query, Int32)</a> is called, queries consult the Similarity's DocScorer for an |
| explanation of how it computed its score. The query passes in a the document id and an explanation of how the frequency |
| was computed. |
| <p> |
| <div class="lucene-block lucene-experimental">This is a Lucene.NET EXPERIMENTAL API, use at your own risk</div></div> |
| <div class="markdown level0 conceptual"></div> |
| <div class="inheritance"> |
| <h5>Inheritance</h5> |
| <div class="level0"><span class="xref">System.Object</span></div> |
| <div class="level1"><span class="xref">Similarity</span></div> |
| <div class="level2"><a class="xref" href="Lucene.Net.Search.Similarities.BM25Similarity.html">BM25Similarity</a></div> |
| <div class="level2"><a class="xref" href="Lucene.Net.Search.Similarities.MultiSimilarity.html">MultiSimilarity</a></div> |
| <div class="level2"><a class="xref" href="Lucene.Net.Search.Similarities.PerFieldSimilarityWrapper.html">PerFieldSimilarityWrapper</a></div> |
| <div class="level2"><a class="xref" href="Lucene.Net.Search.Similarities.SimilarityBase.html">SimilarityBase</a></div> |
| <div class="level2"><a class="xref" href="Lucene.Net.Search.Similarities.TFIDFSimilarity.html">TFIDFSimilarity</a></div> |
| </div> |
| <div class="inheritedMembers"> |
| <h5>Inherited Members</h5> |
| <div> |
| <span class="xref">System.Object.Equals(System.Object)</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.Equals(System.Object, System.Object)</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.GetHashCode()</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.GetType()</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.MemberwiseClone()</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.ReferenceEquals(System.Object, System.Object)</span> |
| </div> |
| <div> |
| <span class="xref">System.Object.ToString()</span> |
| </div> |
| </div> |
| <h6><strong>Namespace</strong>: <a class="xref" href="Lucene.Net.Search.Similarities.html">Lucene.Net.Search.Similarities</a></h6> |
| <h6><strong>Assembly</strong>: Lucene.Net.dll</h6> |
| <h5 id="Lucene_Net_Search_Similarities_Similarity_syntax">Syntax</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public abstract class Similarity</code></pre> |
| </div> |
| <h3 id="constructors">Constructors |
| </h3> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00013/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_Similarities_Similarity__ctor.md&value=---%0Auid%3A%20Lucene.Net.Search.Similarities.Similarity.%23ctor%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/fix/apidocs-layout/src/Lucene.Net/Search/Similarities/Similarity.cs/#L105">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_Similarities_Similarity__ctor_" data-uid="Lucene.Net.Search.Similarities.Similarity.#ctor*"></a> |
| <h4 id="Lucene_Net_Search_Similarities_Similarity__ctor" data-uid="Lucene.Net.Search.Similarities.Similarity.#ctor">Similarity()</h4> |
| <div class="markdown level1 summary"><p>Sole constructor. (For invocation by subclass |
| constructors, typically implicit.)</p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">protected Similarity()</code></pre> |
| </div> |
| <h3 id="methods">Methods |
| </h3> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00013/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_Similarities_Similarity_ComputeNorm_Lucene_Net_Index_FieldInvertState_.md&value=---%0Auid%3A%20Lucene.Net.Search.Similarities.Similarity.ComputeNorm(Lucene.Net.Index.FieldInvertState)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/fix/apidocs-layout/src/Lucene.Net/Search/Similarities/Similarity.cs/#L154">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_Similarities_Similarity_ComputeNorm_" data-uid="Lucene.Net.Search.Similarities.Similarity.ComputeNorm*"></a> |
| <h4 id="Lucene_Net_Search_Similarities_Similarity_ComputeNorm_Lucene_Net_Index_FieldInvertState_" data-uid="Lucene.Net.Search.Similarities.Similarity.ComputeNorm(Lucene.Net.Index.FieldInvertState)">ComputeNorm(FieldInvertState)</h4> |
| <div class="markdown level1 summary"><p>Computes the normalization value for a field, given the accumulated |
| state of term processing for this field (see <a class="xref" href="Lucene.Net.Index.FieldInvertState.html">FieldInvertState</a>).</p> |
| <p><p>Matches in longer fields are less precise, so implementations of this |
| method usually set smaller values when <code>state.Length</code> is large, |
| and larger values when <pre><code>state.Length</code></pre> is small. |
| <p> |
| <div class="lucene-block lucene-experimental">This is a Lucene.NET EXPERIMENTAL API, use at your own risk</div></div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public abstract long ComputeNorm(FieldInvertState state)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Index.FieldInvertState.html">FieldInvertState</a></td> |
| <td><span class="parametername">state</span></td> |
| <td><p>current processing state for this field </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Int64</span></td> |
| <td><p>computed norm value </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00013/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_Similarities_Similarity_ComputeWeight_System_Single_Lucene_Net_Search_CollectionStatistics_Lucene_Net_Search_TermStatistics___.md&value=---%0Auid%3A%20Lucene.Net.Search.Similarities.Similarity.ComputeWeight(System.Single%2CLucene.Net.Search.CollectionStatistics%2CLucene.Net.Search.TermStatistics%5B%5D)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/fix/apidocs-layout/src/Lucene.Net/Search/Similarities/Similarity.cs/#L163">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_Similarities_Similarity_ComputeWeight_" data-uid="Lucene.Net.Search.Similarities.Similarity.ComputeWeight*"></a> |
| <h4 id="Lucene_Net_Search_Similarities_Similarity_ComputeWeight_System_Single_Lucene_Net_Search_CollectionStatistics_Lucene_Net_Search_TermStatistics___" data-uid="Lucene.Net.Search.Similarities.Similarity.ComputeWeight(System.Single,Lucene.Net.Search.CollectionStatistics,Lucene.Net.Search.TermStatistics[])">ComputeWeight(Single, CollectionStatistics, TermStatistics[])</h4> |
| <div class="markdown level1 summary"><p>Compute any collection-level weight (e.g. IDF, average document length, etc) needed for scoring a query.</p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public abstract Similarity.SimWeight ComputeWeight(float queryBoost, CollectionStatistics collectionStats, params TermStatistics[] termStats)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Single</span></td> |
| <td><span class="parametername">queryBoost</span></td> |
| <td><p>the query-time boost. </p> |
| </td> |
| </tr> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Search.CollectionStatistics.html">CollectionStatistics</a></td> |
| <td><span class="parametername">collectionStats</span></td> |
| <td><p>collection-level statistics, such as the number of tokens in the collection. </p> |
| </td> |
| </tr> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Search.TermStatistics.html">TermStatistics</a>[]</td> |
| <td><span class="parametername">termStats</span></td> |
| <td><p>term-level statistics, such as the document frequency of a term across the collection. </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html">Similarity.SimWeight</a></td> |
| <td><p><a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html">Similarity.SimWeight</a> object with the information this <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html">Similarity</a> needs to score a query. </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00013/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_Similarities_Similarity_Coord_System_Int32_System_Int32_.md&value=---%0Auid%3A%20Lucene.Net.Search.Similarities.Similarity.Coord(System.Int32%2CSystem.Int32)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/fix/apidocs-layout/src/Lucene.Net/Search/Similarities/Similarity.cs/#L119">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_Similarities_Similarity_Coord_" data-uid="Lucene.Net.Search.Similarities.Similarity.Coord*"></a> |
| <h4 id="Lucene_Net_Search_Similarities_Similarity_Coord_System_Int32_System_Int32_" data-uid="Lucene.Net.Search.Similarities.Similarity.Coord(System.Int32,System.Int32)">Coord(Int32, Int32)</h4> |
| <div class="markdown level1 summary"><p>Hook to integrate coordinate-level matching. |
| <p> |
| By default this is disabled (returns <code>1</code>), as with |
| most modern models this will only skew performance, but some |
| implementations such as <a class="xref" href="Lucene.Net.Search.Similarities.TFIDFSimilarity.html">TFIDFSimilarity</a> override this.</p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public virtual float Coord(int overlap, int maxOverlap)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Int32</span></td> |
| <td><span class="parametername">overlap</span></td> |
| <td><p>the number of query terms matched in the document </p> |
| </td> |
| </tr> |
| <tr> |
| <td><span class="xref">System.Int32</span></td> |
| <td><span class="parametername">maxOverlap</span></td> |
| <td><p>the total number of terms in the query </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Single</span></td> |
| <td><p>a score factor based on term overlap with the query </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00013/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_Similarities_Similarity_GetSimScorer_Lucene_Net_Search_Similarities_Similarity_SimWeight_Lucene_Net_Index_AtomicReaderContext_.md&value=---%0Auid%3A%20Lucene.Net.Search.Similarities.Similarity.GetSimScorer(Lucene.Net.Search.Similarities.Similarity.SimWeight%2CLucene.Net.Index.AtomicReaderContext)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/fix/apidocs-layout/src/Lucene.Net/Search/Similarities/Similarity.cs/#L171">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_Similarities_Similarity_GetSimScorer_" data-uid="Lucene.Net.Search.Similarities.Similarity.GetSimScorer*"></a> |
| <h4 id="Lucene_Net_Search_Similarities_Similarity_GetSimScorer_Lucene_Net_Search_Similarities_Similarity_SimWeight_Lucene_Net_Index_AtomicReaderContext_" data-uid="Lucene.Net.Search.Similarities.Similarity.GetSimScorer(Lucene.Net.Search.Similarities.Similarity.SimWeight,Lucene.Net.Index.AtomicReaderContext)">GetSimScorer(Similarity.SimWeight, AtomicReaderContext)</h4> |
| <div class="markdown level1 summary"><p>Creates a new <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimScorer.html">Similarity.SimScorer</a> to score matching documents from a segment of the inverted index. </p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public abstract Similarity.SimScorer GetSimScorer(Similarity.SimWeight weight, AtomicReaderContext context)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html">Similarity.SimWeight</a></td> |
| <td><span class="parametername">weight</span></td> |
| <td><p>collection information from <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.html#Lucene_Net_Search_Similarities_Similarity_ComputeWeight_System_Single_Lucene_Net_Search_CollectionStatistics_Lucene_Net_Search_TermStatistics___">ComputeWeight(Single, CollectionStatistics, TermStatistics[])</a> </p> |
| </td> |
| </tr> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Index.AtomicReaderContext.html">AtomicReaderContext</a></td> |
| <td><span class="parametername">context</span></td> |
| <td><p>segment of the inverted index to be scored. </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimScorer.html">Similarity.SimScorer</a></td> |
| <td><p>Sloppy <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimScorer.html">Similarity.SimScorer</a> for scoring documents across <code>context</code> </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="exceptions">Exceptions</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Condition</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.IO.IOException</span></td> |
| <td><p>if there is a low-level I/O error </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <span class="small pull-right mobile-hide"> |
| <span class="divider">|</span> |
| <a href="https://github.com/apache/lucenenet/new/docs/4.8.0-beta00013/websites/apidocs/apiSpec/new?filename=Lucene_Net_Search_Similarities_Similarity_QueryNorm_System_Single_.md&value=---%0Auid%3A%20Lucene.Net.Search.Similarities.Similarity.QueryNorm(System.Single)%0Asummary%3A%20'*You%20can%20override%20summary%20for%20the%20API%20here%20using%20*MARKDOWN*%20syntax'%0A---%0A%0A*Please%20type%20below%20more%20information%20about%20this%20API%3A*%0A%0A">Improve this Doc</a> |
| </span> |
| <span class="small pull-right mobile-hide"> |
| <a href="https://github.com/NightOwl888/lucenenet/blob/fix/apidocs-layout/src/Lucene.Net/Search/Similarities/Similarity.cs/#L137">View Source</a> |
| </span> |
| <a id="Lucene_Net_Search_Similarities_Similarity_QueryNorm_" data-uid="Lucene.Net.Search.Similarities.Similarity.QueryNorm*"></a> |
| <h4 id="Lucene_Net_Search_Similarities_Similarity_QueryNorm_System_Single_" data-uid="Lucene.Net.Search.Similarities.Similarity.QueryNorm(System.Single)">QueryNorm(Single)</h4> |
| <div class="markdown level1 summary"><p>Computes the normalization value for a query given the sum of the |
| normalized weights <a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html#Lucene_Net_Search_Similarities_Similarity_SimWeight_GetValueForNormalization">GetValueForNormalization()</a> of |
| each of the query terms. this value is passed back to the |
| weight (<a class="xref" href="Lucene.Net.Search.Similarities.Similarity.SimWeight.html#Lucene_Net_Search_Similarities_Similarity_SimWeight_Normalize_System_Single_System_Single_">Normalize(Single, Single)</a> of each query |
| term, to provide a hook to attempt to make scores from different |
| queries comparable. |
| <p> |
| By default this is disabled (returns <code>1</code>), but some |
| implementations such as <a class="xref" href="Lucene.Net.Search.Similarities.TFIDFSimilarity.html">TFIDFSimilarity</a> override this.</p> |
| </div> |
| <div class="markdown level1 conceptual"></div> |
| <h5 class="decalaration">Declaration</h5> |
| <div class="codewrapper"> |
| <pre><code class="lang-csharp hljs">public virtual float QueryNorm(float valueForNormalization)</code></pre> |
| </div> |
| <h5 class="parameters">Parameters</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Name</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Single</span></td> |
| <td><span class="parametername">valueForNormalization</span></td> |
| <td><p>the sum of the term normalization values </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h5 class="returns">Returns</h5> |
| <table class="table table-bordered table-striped table-condensed"> |
| <thead> |
| <tr> |
| <th>Type</th> |
| <th>Description</th> |
| </tr> |
| </thead> |
| <tbody> |
| <tr> |
| <td><span class="xref">System.Single</span></td> |
| <td><p>a normalization factor for query weights </p> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| <h3 id="seealso">See Also</h3> |
| <div class="seealso"> |
| <div><a class="xref" href="Lucene.Net.Index.IndexWriterConfig.html#Lucene_Net_Index_IndexWriterConfig_Similarity">Similarity</a></div> |
| <div><a class="xref" href="Lucene.Net.Search.IndexSearcher.html#Lucene_Net_Search_IndexSearcher_Similarity">Similarity</a></div> |
| </div> |
| </article> |
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