Calculate the difference between 2 strings using the Levenshtein distance algorithm - CSharp System

CSharp examples for System:String Algorithm

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Description

Calculate the difference between 2 strings using the Levenshtein distance algorithm

Demo Code


using System;//from  w w w.ja  v a  2  s.  c  o  m

public class Main{
        /// <summary>
        ///     Calculate the difference between 2 strings using the Levenshtein distance algorithm
        /// </summary>
        /// <param name="source1">First string</param>
        /// <param name="source2">Second string</param>
        /// <returns></returns>
        public static int LevenshteinDistance(string source1, string source2) //O(n*m)
        {
            var source1Length = source1.Length;
            var source2Length = source2.Length;

            var matrix = new int[source1Length + 1, source2Length + 1];

            // First calculation, if one entry is empty return full length
            if (source1Length == 0)
                return source2Length;

            if (source2Length == 0)
                return source1Length;

            // Initialization of matrix with row size source1Length and columns size source2Length
            for (var i = 0; i <= source1Length; matrix[i, 0] = i++){}
            for (var j = 0; j <= source2Length; matrix[0, j] = j++){}

            // Calculate rows and collumns distances
            for (var i = 1; i <= source1Length; i++)
            {
                for (var j = 1; j <= source2Length; j++)
                {
                    var cost = (source2[j - 1] == source1[i - 1]) ? 0 : 1;

                    matrix[i, j] = Math.Min(
                        Math.Min(matrix[i - 1, j] + 1, matrix[i, j - 1] + 1),
                        matrix[i - 1, j - 1] + cost);
                }
            }
            // return result
            return matrix[source1Length, source2Length];
        }
}

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