Text jarowinkler distance

JaroWinkler.Distance

1 - Similarity, for code that wants a distance rather than a score.

public static double Distance(ReadOnlySpan<char> a, ReadOnlySpan<char> b, double prefixWeight = 0.1, TextElement element = TextElement.Utf16Unit)

Parameters — a and b are the two strings to compare, prefixWeight is what each shared leading character is worth (0.1 by default) and element says what counts as one character — all three exactly as for Similarity, which this subtracts from 1.

Returns — double, normally in [0, 1] and larger meaning less alike.

Example — a swapped pair of letters, forgiven almost entirely because the prefix agrees.

using Lodestar.Text.Distances;

double d = JaroWinkler.Distance("MARTHA", "MARHTA");   // => 0.0388…

Remarks — the same measure as Similarity, turned round for code that sorts ascending or thresholds with "at most". Nothing else differs.

It inherits Similarity's unvalidated prefixWeight, and inverts its consequence: a weight above 0.25 can push the similarity past 1 and therefore this below zero. A negative distance breaks the assumption that most clustering and nearest-neighbour code makes without stating it, so leave prefixWeight alone unless you have a reason and a test.

Applies to — net10.0, netstandard2.0.

See also — JaroWinkler.Similarity, Jaro.Distance, the Python equivalence table.