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 Lucene.Net.Analysis.TokenAttributes.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.

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.

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

Note

This API is for internal purposes only and might change in incompatible ways in the next release.