Text soundex

Soundex

American Soundex: an initial letter followed by three digits.

public static class Soundex

Example — the collision the algorithm is famous for.

using Lodestar.Text.Phonetics;

string robert = Soundex.Encode("Robert");  // => R163
string rupert = Soundex.Encode("Rupert");  // => R163

Remarks — the oldest of the three and the one most likely to be what an existing system already uses. It keeps the first letter, then maps the rest to digits by articulation — bfpv→1, cgjkqsxz→2, dt→3, l→4, mn→5, r→6 — dropping vowels, and pads or truncates to exactly four characters.

Four characters is why it merges so much: over the 402-word corpus it pins, 101 words share a code with at least one other. That is the point of it — recall first — and the reason not to reach for it when a wrong match is expensive.

Reference behaviour is jellyfish.soundex, matched over 402 words.

Applies to — net10.0, netstandard2.0.

See also — Nysiis, Metaphone, the phonetics index.

Members

Member	What it does
Soundex.Encode	The 4-character Soundex code of one word.