C#实现K-MEDOIDS聚类算法

1、任意选取K个对象作为初始聚类中心（O1,O2,…Oi…Ok）。　　
2）将余下的对象分到各个类中去（该对象与哪一个聚类中心最近就被分配到哪一个聚类簇中）；　　
3）对于每个类（Oi）中，顺序选取一个Or，重复步骤2，计算用Or代替Oi后的误差E=各个点到其对应的中心点欧式距离之和。选择E最小的那个Or来代替Oi。
4）重复步骤3，直到K个medoids固定下来。

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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.IO;   namespace K_medoids {     class Program     {         /// <summary>         /// 程序文本数据文件应位于同一文件夹下         /// </summary>         /// <param name="args"></param>         static void Main(string[] args)         {             var path = string.Empty;             int k = 0;             try             {                 path = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, args[0]);//数据文件路径                 k = Convert.ToInt32(args[1]);             }             catch (Exception)             {                 Console.Write("参数错误");                 return;             }             var reader=new StreamReader(path,Encoding.Default);             var indivadulStr =reader.ReadLine().Trim();//每一行数据的字符串形式             var stanStr= System.Text.RegularExpressions.Regex.Replace(indivadulStr, @" +", " ");             var firstData=stanStr.Split(' ');//第一行数据             var realIndivadul = new Indivaduls();//数据结构体             var db = new List<Indivaduls>();//存放所有数据             foreach (var s in firstData)             {                 realIndivadul.Numbers.Add(Convert.ToDouble(s));             }             db.Add(realIndivadul);             while ((indivadulStr=reader.ReadLine())!=null)             {                 var stringNumber = indivadulStr.Trim().Split(' ');                 var doubleNumber = stringNumber.Select(Convert.ToDouble).ToList();                 db.Add(new Indivaduls(){Numbers =doubleNumber});             }               var initialCenters = new List<Indivaduls>();//聚类初始中心个体             var gap = db.Count/k + 1;             for (int i = 0; i < k; i++)             {                 initialCenters.Add(db[i*gap]);             }             var result=Pam(db, initialCenters);             foreach (var crow in result)             {                 foreach (var number in crow.CenterPoint.Numbers)                 {                     Console.Write(number+"\0");                 }                 Console.Write("\r\n");                 foreach (var point in crow.CrowsPoint)                 {                     foreach (var number in point.Numbers)                     {                         Console.Write(number+"\0");                     }                     Console.Write("\r\n");                 }                 Console.WriteLine("========================");             }             Console.ReadKey();           }       /// <summary>       ///       /// </summary>       /// <param name="indivadulses"></param>       /// <param name="centerPoints"></param>       /// <returns>聚类结果 簇</returns>         public static List<Crows> Pam(List<Indivaduls> indivadulses,List<Indivaduls> centerPoints  )         {             var firstCrows = K_medoids(indivadulses, centerPoints);                           var resultCenterPoints = new List<Indivaduls>();//存放结果中心点             for (int i = 0; i < firstCrows.Count; i++)//循环每一个簇             {                 resultCenterPoints.Add(firstCrows[i].CenterPoint);                 var oldOtherCrows =new List<Crows>();                 oldOtherCrows.AddRange(firstCrows);                 oldOtherCrows.RemoveAt(i);                     var oldDiff = AbsoluteDiff(firstCrows[i], oldOtherCrows);                   var count=firstCrows[i].CrowsPoint.Count;                 for (int j = 0; j < count; j++)//循环每一个簇中的非中心点个体                 {                     //var otherCrowsss = new List<Crows>();//除去要替换的中心点所在的簇 其他簇                     //otherCrowsss.AddRange(firstCrows);                     //otherCrowsss.RemoveAt(i);                       var newCenterPoints = new List<Indivaduls>();//新的中心点集合                     newCenterPoints.AddRange(centerPoints);                     newCenterPoints.RemoveAt(i);                     newCenterPoints.Add(firstCrows[i].CrowsPoint[j]);                       var newOtherCrowsCenterPoints = new List<Indivaduls>();//新的除变化点所在簇的中心 的其他中心点                     newOtherCrowsCenterPoints.AddRange(centerPoints);                     newOtherCrowsCenterPoints.RemoveAt(i);                                           var newCrows = K_medoids(indivadulses,newCenterPoints); //替换点后 新的聚类簇                       var newOtherCrows = new List<Crows>();                     var newCrow = new Crows();                                           foreach (var crow in newCrows)                     {                         if (newOtherCrowsCenterPoints.MyContains(crow.CenterPoint))                         {                             newOtherCrows.Add(crow);                         }                         else                         {                             newCrow = crow;                         }                     }                     var newDiff = AbsoluteDiff(newCrow,newOtherCrows);                     if (newDiff < oldDiff)                     {                         resultCenterPoints[i] = newCrow.CenterPoint;                         oldDiff = newDiff;                     }                   }                               }           var resultCrows= K_medoids(indivadulses, resultCenterPoints);             return resultCrows;         }         /// <summary>         /// 单次聚类         /// </summary>         /// <param name="indivadulses">待聚类个体，包括了中心点</param>         /// <param name="centerPoints">中心点个体</param>         /// <returns>聚类结果</returns>         public static List<Crows> K_medoids(List<Indivaduls> indivadulses,List<Indivaduls> centerPoints)         {             var resultCrows = new List<Crows>();//聚类结果 簇集合             var indivadulsCount = indivadulses.Count;//待分配个体的个数,包括了中心点             for (var i = 0; i < centerPoints.Count; i++)             {                 resultCrows.Add(new Crows() { CenterPoint = centerPoints[i] });             }             for (int i = 0; i < indivadulsCount; i++)             {                 if (!centerPoints.MyContains(indivadulses[i]))                 {                     int myNumber = 0;//要将这个点归类到 序号为0的resultCrows中                     var firstDic = P2PDistance(indivadulses[i], resultCrows[0].CenterPoint);//该点与第一个中心的距离                     for (int j = 1; j < resultCrows.Count; j++)                     {                         var otherDic = P2PDistance(indivadulses[i], resultCrows[j].CenterPoint);                         if (otherDic < firstDic)                         {                             firstDic = otherDic;                             myNumber = j;                         }                     }                     resultCrows[myNumber].CrowsPoint.Add(indivadulses[i]);                 }             }             return resultCrows;         }         /// <summary>         /// 对于已经完成一次聚类后的某一个点center计算绝对误差         /// </summary>         /// <param name="centerCrow">要计算绝对误差的中心点群簇</param>         /// <param name="otherPoints">除中心点群簇外的其他群簇</param>         public static double AbsoluteDiff(Crows centerCrow,List<Crows> otherPoints )         {             var countCrows = otherPoints.Count;             var  distance = Distance(centerCrow);             for (var i = 0; i < countCrows; i++)             {                 distance += Distance(otherPoints[i]);             }             return distance;         }         /// <summary>         /// 计算群簇中各个点距离中心点的欧式距离         /// </summary>         /// <param name="crow">群簇</param>         /// <returns>欧式距离</returns>         public static double Distance(Crows crow)         {             var pointCount = crow.CrowsPoint.Count;//非中心点的个数             var distance = 0.0;//总距离             for (var i = 0; i < pointCount; i++)             {                 distance += P2PDistance(crow.CenterPoint, crow.CrowsPoint[i]);             }             return distance;         }         /// <summary>         /// 两点间欧式距离         /// </summary>         /// <param name="p1">点p1</param>         /// <param name="p2">点p2</param>         /// <returns></returns>         public static double P2PDistance(Indivaduls p1,Indivaduls p2)         {             if (p1.Numbers.Count != p2.Numbers.Count || p1.Numbers.Count == 0)             {                 throw new Exception();             }             var dimension = p1.Numbers.Count;             var result = 0.0;             for (var i = 0; i < dimension; i++)             {                 result += (p1.Numbers[i] - p2.Numbers[i])*(p1.Numbers[i] - p2.Numbers[i]);             }             return Math.Sqrt(result);         }       }     /// <summary>     /// 一个点个体     /// </summary>     public class Indivaduls     {         public List<double> Numbers;         public Indivaduls()         {             this.Numbers=new List<double>();         }         public  bool MyEquals(Indivaduls obj)         {             if (obj.Numbers.Count != this.Numbers.Count)                 return false;             for (int i = 0; i < Numbers.Count; i++)             {                 if (this.Numbers[i] != obj.Numbers[i])                     return false;             }             return true;         }     }     /// <summary>     /// 一个聚类簇     /// </summary>     public class Crows     {         public Crows()         {             this.CrowsPoint=new List<Indivaduls>();             this.CenterPoint=new Indivaduls();         }         public List<Indivaduls> CrowsPoint;//簇中除中心点外的其他个体点         public Indivaduls CenterPoint;//聚类簇中心点     }     public static class ExpandList     {         /// <summary>         /// 扩展方法、判断该集合中是否存在point个体         /// </summary>         /// <param name="indivadulses"></param>         /// <param name="point"></param>         /// <returns></returns>         public static bool MyContains(this List<Indivaduls> indivadulses,Indivaduls point)         {             foreach (var indivadulse in indivadulses)             {                 if (point.MyEquals(indivadulse))                   return true;             }             return false;         }     } }