Getting the closest string match

Question

I need a way to compare multiple strings to a test string and return the string that closely resembles it:

TEST STRING: THE BROWN FOX JUMPED OVER THE RED COW         


        

Answer 1

A sample using C# is here.

public static void Main()
{
    Console.WriteLine("Hello World " + LevenshteinDistance("Hello","World"));
    Console.WriteLine("Choice A " + LevenshteinDistance("THE BROWN FOX JUMPED OVER THE RED COW","THE RED COW JUMPED OVER THE GREEN CHICKEN"));
    Console.WriteLine("Choice B " + LevenshteinDistance("THE BROWN FOX JUMPED OVER THE RED COW","THE RED COW JUMPED OVER THE RED COW"));
    Console.WriteLine("Choice C " + LevenshteinDistance("THE BROWN FOX JUMPED OVER THE RED COW","THE RED FOX JUMPED OVER THE BROWN COW"));
}

public static float LevenshteinDistance(string a, string b)
{
    var rowLen = a.Length;
    var colLen = b.Length;
    var maxLen = Math.Max(rowLen, colLen);

    // Step 1
    if (rowLen == 0 || colLen == 0)
    {
        return maxLen;
    }

    /// Create the two vectors
    var v0 = new int[rowLen + 1];
    var v1 = new int[rowLen + 1];

    /// Step 2
    /// Initialize the first vector
    for (var i = 1; i <= rowLen; i++)
    {
        v0[i] = i;
    }

    // Step 3
    /// For each column
    for (var j = 1; j <= colLen; j++)
    {
        /// Set the 0'th element to the column number
        v1[0] = j;

        // Step 4
        /// For each row
        for (var i = 1; i <= rowLen; i++)
        {
            // Step 5
            var cost = (a[i - 1] == b[j - 1]) ? 0 : 1;

            // Step 6
            /// Find minimum
            v1[i] = Math.Min(v0[i] + 1, Math.Min(v1[i - 1] + 1, v0[i - 1] + cost));
        }

        /// Swap the vectors
        var vTmp = v0;
        v0 = v1;
        v1 = vTmp;
    }

    // Step 7
    /// The vectors were swapped one last time at the end of the last loop,
    /// that is why the result is now in v0 rather than in v1
    return v0[rowLen];
}

The output is:

Hello World 4
Choice A 15
Choice B 6
Choice C 8