Are There Any Fuzzy Search or String Similarity Functions Libraries Written for C#

Are there any Fuzzy Search or String Similarity Functions libraries written for C#?

Levenshtein distance implementation:

• Using LINQ (not really, see comments)
• Not using LINQ

I have a .NET 1.1 project in which I use the latter. It's simplistic, but works perfectly for what I need. From what I remember it needed a bit of tweaking, but nothing that wasn't obvious.

Fuzzy match in C#

Current versions don't have it built in.

I have seen and used Soundex (a method for fuzzy matching) operations for this in the past. Here's an article on how to implement Soundex in .Net.

http://www.codeproject.com/KB/aspnet/Soundex.aspx

Compare string similarity

static class LevenshteinDistance
{
    public static int Compute(string s, string t)
    {
        if (string.IsNullOrEmpty(s))
        {
            if (string.IsNullOrEmpty(t))
                return 0;
            return t.Length;
        }

        if (string.IsNullOrEmpty(t))
        {
            return s.Length;
        }

        int n = s.Length;
        int m = t.Length;
        int[,] d = new int[n + 1, m + 1];

        // initialize the top and right of the table to 0, 1, 2, ...
        for (int i = 0; i <= n; d[i, 0] = i++);
        for (int j = 1; j <= m; d[0, j] = j++);

        for (int i = 1; i <= n; i++)
        {
            for (int j = 1; j <= m; j++)
            {
                int cost = (t[j - 1] == s[i - 1]) ? 0 : 1;
                int min1 = d[i - 1, j] + 1;
                int min2 = d[i, j - 1] + 1;
                int min3 = d[i - 1, j - 1] + cost;
                d[i, j] = Math.Min(Math.Min(min1, min2), min3);
            }
        }
        return d[n, m];
    }
}

Fuzzy Text Matching C#

Let me introduce you to the Levenshtein distance formula. It is awesome:

http://en.wikipedia.org/wiki/Levenshtein_distance

In information theory and computer science, the Levenshtein distance is a string metric for measuring the amount of difference between two sequences. The term edit distance is often used to refer specifically to Levenshtein distance.

Personally I used this in a healthcare setting, where Provider names were checked for duplicates. Using the Levenshtein process, we gave them a confidence rating and allowed them to determine if it was a true duplicate or something unique.

How can I check the input if it's nearly same or not?

Google shows me this

Approximate string matching

There are various string distance metrics you could use.

I would recommend Jaro-Winkler. Unlike edit-distance where the result of a comparison is in discrete units of edits, JW gives you a 0-1 score. It is especially suited for proper names. Also look at this nice tutorial and this SO question.

I haven't worked with C# but here are some implementations of JW I found online:

Impl 1 (They have a DOT NET version too if you look at the file list)

Impl 2

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If you want to do a bit more sophisticated matching, you can try to do some custom normalization of word forms commonly occurring in company names such as ltd/limited, inc/incorporated, corp/corporation to account for case insensitivity, abbreviations etc. This way if you compute

distance (normalize("foo corp."),
normalize("FOO CORPORATION") )

you should get the result to be 0 rather than 14 (which is what you would get if you computed levenshtein edit-distance).

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