Namespace Lucene.Net.Analysis.Pt

Analyzer for Portuguese.

Classes

PortugueseAnalyzer

Lucene.Net.Analysis.Analyzer for Portuguese.

You must specify the required Lucene.Net.Util.LuceneVersion compatibility when creating PortugueseAnalyzer:

• As of 3.6, PortugueseLightStemFilter is used for less aggressive stemming.

PortugueseLightStemFilter

A Lucene.Net.Analysis.TokenFilter that applies PortugueseLightStemmer to stem Portuguese words.

To prevent terms from being stemmed use an instance of SetKeywordMarkerFilter or a custom Lucene.Net.Analysis.TokenFilter that sets the KeywordAttribute before this Lucene.Net.Analysis.TokenStream.

PortugueseLightStemFilterFactory

Factory for PortugueseLightStemFilter.

<fieldType name="text_ptlgtstem" class="solr.TextField" positionIncrementGap="100">
  <analyzer>
    <tokenizer class="solr.StandardTokenizerFactory"/>
    <filter class="solr.LowerCaseFilterFactory"/>
    <filter class="solr.PortugueseLightStemFilterFactory"/>
  </analyzer>
</fieldType>

PortugueseLightStemmer

Light Stemmer for Portuguese

This stemmer implements the "UniNE" algorithm in: Light Stemming Approaches for the French, Portuguese, German and Hungarian Languages Jacques Savoy

PortugueseMinimalStemFilter

A Lucene.Net.Analysis.TokenFilter that applies PortugueseMinimalStemmer to stem Portuguese words.

To prevent terms from being stemmed use an instance of SetKeywordMarkerFilter or a custom Lucene.Net.Analysis.TokenFilter that sets the KeywordAttribute before this Lucene.Net.Analysis.TokenStream.

PortugueseMinimalStemFilterFactory

Factory for PortugueseMinimalStemFilter.

<fieldType name="text_ptminstem" class="solr.TextField" positionIncrementGap="100">
  <analyzer>
    <tokenizer class="solr.StandardTokenizerFactory"/>
    <filter class="solr.LowerCaseFilterFactory"/>
    <filter class="solr.PortugueseMinimalStemFilterFactory"/>
  </analyzer>
</fieldType>

PortugueseMinimalStemmer

Minimal Stemmer for Portuguese

This follows the "RSLP-S" algorithm presented in: A study on the Use of Stemming for Monolingual Ad-Hoc Portuguese Information Retrieval (Orengo, et al) which is just the plural reduction step of the RSLP algorithm from A Stemming Algorithm for the Portuguese Language, Orengo et al.

PortugueseStemFilter

A Lucene.Net.Analysis.TokenFilter that applies PortugueseStemmer to stem Portuguese words.

To prevent terms from being stemmed use an instance of SetKeywordMarkerFilter or a custom Lucene.Net.Analysis.TokenFilter that sets the KeywordAttribute before this Lucene.Net.Analysis.TokenStream.

PortugueseStemFilterFactory

Factory for PortugueseStemFilter.

<fieldType name="text_ptstem" class="solr.TextField" positionIncrementGap="100">
  <analyzer>
    <tokenizer class="solr.StandardTokenizerFactory"/>
    <filter class="solr.LowerCaseFilterFactory"/>
    <filter class="solr.PortugueseStemFilterFactory"/>
  </analyzer>
</fieldType>

PortugueseStemmer

Portuguese stemmer implementing the RSLP (Removedor de Sufixos da Lingua Portuguesa) algorithm. This is sometimes also referred to as the Orengo stemmer.

RSLPStemmerBase

Base class for stemmers that use a set of RSLP-like stemming steps.

RSLP (Removedor de Sufixos da Lingua Portuguesa) is an algorithm designed originally for stemming the Portuguese language, described in the paper A Stemming Algorithm for the Portuguese Language, Orengo et. al.

Since this time a plural-only modification (RSLP-S) as well as a modification for the Galician language have been implemented. This class parses a configuration file that describes RSLPStemmerBase.Steps, where each RSLPStemmerBase.Step contains a set of RSLPStemmerBase.Rules.

The general rule format is:

{ "suffix", N, "replacement", { "exception1", "exception2", ...}}

where:

• suffix is the suffix to be removed (such as "inho").
• N is the min stem size, where stem is defined as the candidate stem after removing the suffix (but before appending the replacement!)
• replacement is an optimal string to append after removing the suffix. This can be the empty string.
• exceptions is an optional list of exceptions, patterns that should not be stemmed. These patterns can be specified as whole word or suffix (ends-with) patterns, depending upon the exceptions format flag in the step header.

A step is an ordered list of rules, with a structure in this format:

{ "name", N, B, { "cond1", "cond2", ... } ... rules ... };

where:

• name is a name for the step (such as "Plural").
• N is the min word size. Words that are less than this length bypass the step completely, as an optimization. Note: N can be zero, in this case this implementation will automatically calculate the appropriate value from the underlying rules.
• B is a "boolean" flag specifying how exceptions in the rules are matched. A value of 1 indicates whole-word pattern matching, a value of 0 indicates that exceptions are actually suffixes and should be matched with ends-with.
• conds are an optional list of conditions to enter the step at all. If the list is non-empty, then a word must end with one of these conditions or it will bypass the step completely as an optimization.

RSLP description

This is a Lucene.NET INTERNAL API, use at your own risk

RSLPStemmerBase.Rule

A basic rule, with no exceptions.

RSLPStemmerBase.RuleWithSetExceptions

A rule with a set of whole-word exceptions.

RSLPStemmerBase.RuleWithSuffixExceptions

A rule with a set of exceptional suffixes.

RSLPStemmerBase.Step

A step containing a list of rules.