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| <h1 id="Lucene_Net_Search_Suggest_Analyzing" data-uid="Lucene.Net.Search.Suggest.Analyzing" class="text-break">Namespace Lucene.Net.Search.Suggest.Analyzing |
| </h1> |
| <div class="markdown level0 summary"><!-- |
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| <p>Analyzer based autosuggest.</p> |
| </div> |
| <div class="markdown level0 conceptual"></div> |
| <div class="markdown level0 remarks"></div> |
| <h3 id="classes">Classes |
| </h3> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.AnalyzingInfixSuggester.html">AnalyzingInfixSuggester</a></h4> |
| <section><p>Analyzes the input text and then suggests matches based |
| on prefix matches to any tokens in the indexed text. |
| This also highlights the tokens that match.</p> |
| <p>This suggester supports payloads. Matches are sorted only |
| by the suggest weight; it would be nice to support |
| blended score + weight sort in the future. This means |
| this suggester best applies when there is a strong |
| a-priori ranking of all the suggestions. |
| |
| </p> |
| <p>This suggester supports contexts, however the |
| contexts must be valid utf8 (arbitrary binary terms will |
| not work). |
| |
| @lucene.experimental |
| </p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.AnalyzingSuggester.html">AnalyzingSuggester</a></h4> |
| <section><p>Suggester that first analyzes the surface form, adds the |
| analyzed form to a weighted FST, and then does the same |
| thing at lookup time. This means lookup is based on the |
| analyzed form while suggestions are still the surface |
| form(s).</p> |
| <p> |
| This can result in powerful suggester functionality. For |
| example, if you use an analyzer removing stop words, |
| then the partial text "ghost chr..." could see the |
| suggestion "The Ghost of Christmas Past". Note that |
| position increments MUST NOT be preserved for this example |
| to work, so you should call the constructor with |
| <span class="xref">Lucene.Net.Search.Suggest.Analyzing.AnalyzingSuggester.preservePositionIncrements</span> parameter set to |
| false |
| |
| </p> |
| <p> |
| If SynonymFilter is used to map wifi and wireless network to |
| hotspot then the partial text "wirele..." could suggest |
| "wifi router". Token normalization like stemmers, accent |
| removal, etc., would allow suggestions to ignore such |
| variations. |
| |
| </p> |
| <p> |
| When two matching suggestions have the same weight, they |
| are tie-broken by the analyzed form. If their analyzed |
| form is the same then the order is undefined. |
| |
| </p> |
| <p> |
| There are some limitations: |
| <ol><li> A lookup from a query like "net" in English won't |
| be any different than "net " (ie, user added a |
| trailing space) because analyzers don't reflect |
| when they've seen a token separator and when they |
| haven't.</li><li> If you're using <span class="xref">Lucene.Net.Analysis.Core.StopFilter</span>, and the user will |
| type "fast apple", but so far all they've typed is |
| "fast a", again because the analyzer doesn't convey whether |
| it's seen a token separator after the "a", |
| <span class="xref">Lucene.Net.Analysis.Core.StopFilter</span> will remove that "a" causing |
| far more matches than you'd expect.</li><li> Lookups with the empty string return no results |
| instead of all results.</li></ol> |
| |
| @lucene.experimental |
| </p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.BlendedInfixSuggester.html">BlendedInfixSuggester</a></h4> |
| <section><p>Extension of the <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.AnalyzingInfixSuggester.html">AnalyzingInfixSuggester</a> which transforms the weight |
| after search to take into account the position of the searched term into |
| the indexed text. |
| Please note that it increases the number of elements searched and applies the |
| ponderation after. It might be costly for long suggestions.</p> |
| <div class="lucene-block lucene-experimental">This is a Lucene.NET EXPERIMENTAL API, use at your own risk</div></section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FreeTextSuggester.html">FreeTextSuggester</a></h4> |
| <section><p>Builds an ngram model from the text sent to <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FreeTextSuggester.html#Lucene_Net_Search_Suggest_Analyzing_FreeTextSuggester_Build_Lucene_Net_Search_Suggest_IInputIterator_System_Double_">Build(IInputIterator, Double)</a> |
| and predicts based on the last grams-1 tokens in |
| the request sent to <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FreeTextSuggester.html#Lucene_Net_Search_Suggest_Analyzing_FreeTextSuggester_DoLookup_System_String_System_Collections_Generic_IEnumerable_Lucene_Net_Util_BytesRef__System_Boolean_System_Int32_">DoLookup(String, IEnumerable<BytesRef>, Boolean, Int32)</a>. This tries to |
| handle the "long tail" of suggestions for when the |
| incoming query is a never before seen query string.</p> |
| <p>Likely this suggester would only be used as a |
| fallback, when the primary suggester fails to find |
| any suggestions. |
| |
| </p> |
| <p>Note that the weight for each suggestion is unused, |
| and the suggestions are the analyzed forms (so your |
| analysis process should normally be very "light"). |
| |
| </p> |
| <p>This uses the stupid backoff language model to smooth |
| scores across ngram models; see |
| <a href="http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.76.1126"> |
| "Large language models in machine translation"</a> for details. |
| |
| </p> |
| <p> From <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FreeTextSuggester.html#Lucene_Net_Search_Suggest_Analyzing_FreeTextSuggester_DoLookup_System_String_System_Collections_Generic_IEnumerable_Lucene_Net_Util_BytesRef__System_Boolean_System_Int32_">DoLookup(String, IEnumerable<BytesRef>, Boolean, Int32)</a>, the key of each result is the |
| ngram token; the value is <span class="xref">System.Int64.MaxValue</span> * score (fixed |
| point, cast to long). Divide by <span class="xref">System.Int64.MaxValue</span> to get |
| the score back, which ranges from 0.0 to 1.0. |
| |
| <code>onlyMorePopular</code> is unused. |
| |
| @lucene.experimental |
| </p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FSTUtil.html">FSTUtil</a></h4> |
| <section><p>Exposes a utility method to enumerate all paths |
| intersecting an <span class="xref">Lucene.Net.Util.Automaton.Automaton</span> with an <a class="xref" href="http://localhost:8080/api/core/Lucene.Net.Util.Fst.FST.html">FST</a>.</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FSTUtil.Path-1.html">FSTUtil.Path<T></a></h4> |
| <section><p>Holds a pair (automaton, fst) of states and accumulated output in the intersected machine. </p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.html">FuzzySuggester</a></h4> |
| <section><p>Implements a fuzzy <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.AnalyzingSuggester.html">AnalyzingSuggester</a>. The similarity measurement is |
| based on the Damerau-Levenshtein (optimal string alignment) algorithm, though |
| you can explicitly choose classic Levenshtein by passing <code>false</code> |
| for the <span class="xref">Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.transpositions</span> parameter. |
| <p> |
| At most, this query will match terms up to <a class="xref" href="http://localhost:8080/api/core/Lucene.Net.Util.Automaton.LevenshteinAutomata.html#Lucene_Net_Util_Automaton_LevenshteinAutomata_MAXIMUM_SUPPORTED_DISTANCE">MAXIMUM_SUPPORTED_DISTANCE</a> |
| edits. Higher distances are not supported. Note that the |
| fuzzy distance is measured in "byte space" on the bytes |
| returned by the <span class="xref">Lucene.Net.Analysis.TokenStream</span>'s <a class="xref" href="http://localhost:8080/api/core/Lucene.Net.Analysis.TokenAttributes.ITermToBytesRefAttribute.html">ITermToBytesRefAttribute</a>, |
| usually UTF8. By default |
| the analyzed bytes must be at least 3 <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.html#Lucene_Net_Search_Suggest_Analyzing_FuzzySuggester_DEFAULT_MIN_FUZZY_LENGTH">DEFAULT_MIN_FUZZY_LENGTH</a> |
| bytes before any edits are |
| considered. Furthermore, the first 1 <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.html#Lucene_Net_Search_Suggest_Analyzing_FuzzySuggester_DEFAULT_NON_FUZZY_PREFIX">DEFAULT_NON_FUZZY_PREFIX</a> |
| byte is not allowed to be |
| edited. We allow up to 1 <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.html#Lucene_Net_Search_Suggest_Analyzing_FuzzySuggester_DEFAULT_MAX_EDITS">DEFAULT_MAX_EDITS</a> |
| edit. |
| If <span class="xref">Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.unicodeAware</span> parameter in the constructor is set to true, maxEdits, |
| minFuzzyLength, transpositions and nonFuzzyPrefix are measured in Unicode code |
| points (actual letters) instead of bytes. </p> |
| <p> |
| <p> |
| NOTE: This suggester does not boost suggestions that |
| required no edits over suggestions that did require |
| edits. This is a known limitation.</p> |
| <p> |
| <p> |
| Note: complex query analyzers can have a significant impact on the lookup |
| performance. It's recommended to not use analyzers that drop or inject terms |
| like synonyms to keep the complexity of the prefix intersection low for good |
| lookup performance. At index time, complex analyzers can safely be used. |
| </p></p> |
| <div class="lucene-block lucene-experimental">This is a Lucene.NET EXPERIMENTAL API, use at your own risk</div></section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.SuggestStopFilter.html">SuggestStopFilter</a></h4> |
| <section><p>Like <span class="xref">Lucene.Net.Analysis.Core.StopFilter</span> except it will not remove the |
| last token if that token was not followed by some token |
| separator. For example, a query 'find the' would |
| preserve the 'the' since it was not followed by a space or |
| punctuation or something, and mark it KEYWORD so future |
| stemmers won't touch it either while a query like "find |
| the popsicle' would remove 'the' as a stopword.</p> |
| <p> |
| Normally you'd use the ordinary <span class="xref">Lucene.Net.Analysis.Core.StopFilter</span> |
| in your indexAnalyzer and then this class in your |
| queryAnalyzer, when using one of the analyzing suggesters. |
| </p> |
| </section> |
| <h3 id="enums">Enums |
| </h3> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.BlendedInfixSuggester.BlenderType.html">BlendedInfixSuggester.BlenderType</a></h4> |
| <section><p>The different types of blender.</p> |
| </section> |
| <h4><a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.SuggesterOptions.html">SuggesterOptions</a></h4> |
| <section><p>LUCENENET specific type for specifying <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.AnalyzingSuggester.html">AnalyzingSuggester</a> |
| and <a class="xref" href="Lucene.Net.Search.Suggest.Analyzing.FuzzySuggester.html">FuzzySuggester</a> options. </p> |
| </section> |
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