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DutchSnowballStemmer.Stem

The Snowball stem of one Dutch word.

public static string Stem(string word)

Parameters — word is a single Dutch word. It is lowercased and NFC-normalised before the rules run, so a decomposed é and a composed one fold to the same e.

Returns — string, the stem, always lowercase and free of the umlauts and acutes the input may have carried.

Exceptions — ArgumentNullException when word is null. An empty string, or a word of one character, is returned lowercased and accent-folded and otherwise untouched.

Example — an accent folded away, and a doubled vowel undoubled on the way out.

using Lodestar.Text.Stemming;

string accented = DutchSnowballStemmer.Stem("één");  // => een
string singular = DutchSnowballStemmer.Stem("maan");  // => man
string plural = DutchSnowballStemmer.Stem("manen");  // => man

Remarks — maan → man is the result most likely to look like a bug, and it is the point: Dutch spells the same vowel with one letter in an open syllable and two in a closed one, so manen would never meet maan without the last step undoubling it.

heden is the other rule worth knowing. It becomes heid before anything else runs, which is why mogelijkheden and mogelijkheid both reach mogelijk — the plural is rewritten into the singular and then stripped once, rather than stripped twice by two different rules.

using Lodestar.Text.Stemming;

string plural = DutchSnowballStemmer.Stem("mogelijkheden");  // => mogelijk
string singular = DutchSnowballStemmer.Stem("mogelijkheid");  // => mogelijk

Applies to — net10.0, netstandard2.0.

See also — DutchSnowballStemmer, the stemming index.