C# Levenshtein計算字符串的類似度

 

        static void Main(string[] args)
        {

            Levenshtein(@"今每天氣不錯", @"今天的天氣不錯啊");

            Console.Read();
        }

        /// <summary>
        /// 字符串類似度計算
        /// </summary>
        /// <param name="str1"></param>
        /// <param name="str2"></param>
        public static void Levenshtein(String str1, String str2)
        {
            //計算兩個字符串的長度。  
            int len1 = str1.Length;
            int len2 = str2.Length;
            //創建上面說的數組，比字符長度大一個空間  
            int[,] dif = new int[len1 + 1, len2 + 1];
            //賦初值，步驟B。  
            for (int a = 0; a <= len1; a++)
            {
                dif[a, 0] = a;
            }
            for (int a = 0; a <= len2; a++)
            {
                dif[0, a] = a;
            }
            //計算兩個字符是否同樣，計算左上的值  
            int temp;
            for (int i = 1; i <= len1; i++)
            {
                for (int j = 1; j <= len2; j++)
                {
                    if (str1[i - 1] == str2[j - 1])
                    {
                        temp = 0;
                    }
                    else
                    {
                        temp = 1;
                    }
                    //取三個值中最小的  
                    dif[i, j] = min(dif[i - 1, j - 1] + temp, dif[i, j - 1] + 1,
                            dif[i - 1, j] + 1);
                }
            }
            Console.WriteLine("字符串\"" + str1 + "\"與\"" + str2 + "\"的比較");
            //取數組右下角的值，一樣不一樣位置表明不一樣字符串的比較  
            Console.WriteLine("差別步驟：" + dif[len1, len2]);
            //計算類似度  
            float similarity = 1 - (float)dif[len1, len2] / Math.Max(str1.Length, str2.Length);
            Console.WriteLine("類似度：" + similarity + " 越接近1越類似");
        }

        /// <summary>
        /// 獲得最小值
        /// </summary>
        /// <param name="num"></param>
        /// <returns></returns>
        private static int min(params int[] num)
        {
            int min = Int32.MaxValue;
            foreach (var n in num)
            {
                if (min > n)
                {
                    min = n;
                }
            }
            return min;
        }