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SwedishSnowballStemmer

Swedish stemming by the Snowball algorithm.

public static class SwedishSnowballStemmer

Example — a noun, its plural and its definite plural, collapsed onto one key.

using Lodestar.Text.Stemming;

string singular = SwedishSnowballStemmer.Stem("flickor");  // => flick
string plural = SwedishSnowballStemmer.Stem("flickorna");  // => flick
string genitive = SwedishSnowballStemmer.Stem("flickornas");  // => flick

Remarks — Swedish is the shortest of the eight: three steps, all of them in R1, with no R2 and no RV region. Three things about it are worth knowing before reading a stem.

The region is part of the search, not a test after it. Each step looks for the longest suffix that lies in R1 — not the longest suffix, checked against R1 afterwards. nyheter ends with heter, which reaches past R1, and with er, which does not; er is the one that goes, and the word stems to nyhet. This is the rule the German stemmer next door states the other way round, and it is the one most likely to be got wrong by hand.

Nothing is folded, before or after. ä, å and ö are letters of the Swedish alphabet, all three count as vowels, and all three come back exactly as they went in — so tjänstemännens stems to tjänstemän and not to tjansteman.

Two of the endings are rewritten rather than stripped. löst becomes lös and fullt becomes full, so hjälplöst and kärleksfullt keep a stem that is still a Swedish word.

R1 is floored at three characters as in German, which is what stops short words from being trimmed to nothing — the job RV does in the Romance languages. hos and os come back whole for that reason, and so does cirkus, whose s follows a u rather than one of the seventeen letters the algorithm accepts before a bare s.

Reference behaviour is nltk.stem.snowball.SnowballStemmer("swedish"), matched over 211 words.

Applies to — net10.0, netstandard2.0.

See also — the stemming index.

Members

Member	What it does
SwedishSnowballStemmer.Stem	The Snowball stem of one Swedish word.