String similarity

Edit distance

// The number of insertions, deletions and substitutions that turn one word into the other
Assert.Equal(3, StringSearchUtilities.Levenshtein("kitten", "sitting"));

// With a maximum distance, the computation stops early and returns maxDistance + 1
Assert.Equal(2, StringSearchUtilities.Levenshtein("kitten", "sitting", maxDistance: 1));

// Compare one word with many candidates
var commands = new[] { "build", "test", "publish" };
Assert.Equal([1, 4, 5], StringSearchUtilities.LevenshteinBatch("buid", commands));

• Levenshtein returns the number of single-character insertions, deletions and substitutions needed to turn one string into the other. Use it to suggest the closest command or option when the user makes a typo.
• With maxDistance, the computation stops as soon as the distance is known to be greater, and returns maxDistance + 1. Pass it when you only care about close matches.
• LevenshteinBatch compares a word with many candidates, in parallel, and returns one distance per candidate. maxDegreeOfParallelism limits the number of threads (-1, the default, lets the runtime decide).

Hamming distance

// The number of positions at which two strings of the same length differ
Assert.Equal(3, StringSearchUtilities.Hamming("karolin", "kathrin"));

// The number of different bits of two integers
Assert.Equal(2u, StringSearchUtilities.Hamming(0b1010u, 0b0110u));

Hamming counts the positions where two sequences of the same length differ: strings, any sequences, or the bits of two uint values. Sequences of different lengths throw an ArgumentException.

Phonetic codes

// Names that sound alike get the same code
Assert.Equal("R163", StringSearchUtilities.SoundexEnglish("Robert"));
Assert.Equal("R163", StringSearchUtilities.SoundexEnglish("Rupert"));
Assert.Equal(StringSearchUtilities.Metaphone("Smith"), StringSearchUtilities.Metaphone("Smyth"));

Phonetic algorithms give the same code to words that sound alike, to find names despite spelling variations:

Store the code next to the name, and search by code.

Short names

ShortName.Create computes short names that are unique within a collection, for instance to name columns or files with a length limit:

// Create short names for a collection
var names = new[] { "CustomerName", "CustomerNumber", "CustomerAddress" };
var shortNames = ShortName.Create(names, maxLength: 5, StringComparer.OrdinalIgnoreCase);
Assert.Equal("Custo", shortNames["CustomerName"]);
Assert.Equal("Custm", shortNames["CustomerNumber"]);
Assert.Equal("Custe", shortNames["CustomerAddress"]);

The other overloads create one short name that does not collide with a set of existing short names, and return null when no unique short name fits in the maximum length.