Class | Ferret::Analysis::StemFilter |
In: |
ext/r_analysis.c
|
Parent: | Ferret::Analysis::TokenStream |
A StemFilter takes a term and transforms the term as per the SnowBall stemming algorithm. Note: the input to the stemming filter must already be in lower case, so you will need to use LowerCaseFilter or lowercasing Tokenizer further down the Tokenizer chain in order for this to work properly!
Algorithm Algorithm Pseudonyms Encoding ---------------------------------------------------------------- "danish", | "da", "dan" | "ISO_8859_1", "UTF_8" "dutch", | "dut", "nld" | "ISO_8859_1", "UTF_8" "english", | "en", "eng" | "ISO_8859_1", "UTF_8" "finnish", | "fi", "fin" | "ISO_8859_1", "UTF_8" "french", | "fr", "fra", "fre" | "ISO_8859_1", "UTF_8" "german", | "de", "deu", "ge", "ger" | "ISO_8859_1", "UTF_8" "hungarian", | "hu", "hun" | "ISO_8859_1", "UTF_8" "italian", | "it", "ita" | "ISO_8859_1", "UTF_8" "norwegian", | "nl", "no" | "ISO_8859_1", "UTF_8" "porter", | | "ISO_8859_1", "UTF_8" "portuguese", | "por", "pt" | "ISO_8859_1", "UTF_8" "romanian", | "ro", "ron", "rum" | "ISO_8859_2", "UTF_8" "russian", | "ru", "rus" | "KOI8_R", "UTF_8" "spanish", | "es", "esl" | "ISO_8859_1", "UTF_8" "swedish", | "sv", "swe" | "ISO_8859_1", "UTF_8" "turkish", | "tr", "tur" | "UTF_8"
The following stemmers have recently benn added. Please try them out;
* Hungarian * Romanian * Turkish
To use this filter with other analyzers, you‘ll want to write an Analyzer class that sets up the TokenStream chain as you want it. To use this with a lowercasing Tokenizer, for example, you‘d write an analyzer like this:
def MyAnalyzer < Analyzer def token_stream(field, str) return StemFilter.new(LowerCaseFilter.new(StandardTokenizer.new(str))) end end "debate debates debated debating debater" => ["debat", "debat", "debat", "debat", "debat"]
token_stream: | TokenStream to be filtered |
algorithm: | The algorithm (or language) to use (default: "english") |
encoding: | The encoding of the data (default: "UTF-8") |
Create an StemFilter which uses a snowball stemmer (thank you Martin Porter) to stem words. You can optionally specify the algorithm (default: "english") and encoding (default: "UTF-8").
token_stream: | TokenStream to be filtered |
algorithm: | The algorithm (or language) to use |
encoding: | The encoding of the data (default: "UTF-8") |