K-中心点聚类算法
(1)任意选择k个对象作为初始的簇中心点
(2)指派每个剩余对象给离他最近的中心点所表示的簇
(3)选择一个未被选择的中心点直到所有的中心点都被选择过
(4)选择一个未被选择过的非中心点对象,计算用代替的总代价并记录在S中
,直到所有非中心点都被选择过。
(5)如果在S中的所有非中心点代替所有中心点后的计算出总代价有小于0的存在,然后找出S中的用非中心点替代中心点后代价最小的一个,并用该非中心点替代对应的中心点,形成一个新的k个中心点的集合
(6)重复步骤2-5,直到没有再发生簇的重新分配,即所有的S都大于0.
代码
public class Cluster {private int id;// 标识private Point center;// 中心private List<Point> members = new ArrayList<Point>();// 成员public Cluster(int id, Point center) {this.id = id;this.center = center;}public Cluster(int id, Point center, List<Point> members) {this.id = id;this.center = center;this.members = members;}public void addPoint(Point newPoint) {if (!members.contains(newPoint)){members.add(newPoint);}else{System.out.println("样本数据点 {"+newPoint.toString()+"} 已经存在!");}}public float getdis() {float cur=0;for (Point point : members) {cur+=point.getDist()*point.getDist();}return cur;}public int getId() {return id;}public Point getCenter() {return center;}public void setCenter(Point center) {this.center = center;}public List<Point> getMembers() {return members;}@Overridepublic String toString() {String toString = "-----------Cluster"+this.getId()+"---------\n";toString+="Mid_Point: "+center+" Points_num: "+members.size();for (Point point : members) {toString+="\n"+point.toString();}return toString+"\n";}
}
public class datahandler {public static List<float[]> readTxt(String fileName){List<float[]> list=new ArrayList<>();try {File filename = new File(fileName); // 读取input.txt文件InputStreamReader reader = new InputStreamReader(new FileInputStream(filename)); // 建立一个输入流对象readerBufferedReader br = new BufferedReader(reader);String line = "";line = br.readLine();while (true) {line = br.readLine();if(line==null) break;String[] temp=line.split(",");float[] c=new float[temp.length];for(int i=0;i<temp.length;i++){c[i]=Float.parseFloat(temp[i]);}list.add(c);}} catch (Exception e) {e.printStackTrace();}return list;}public static void writeTxt(String content){try { // 防止文件建立或读取失败,用catch捕捉错误并打印,也可以throw/* 读入TXT文件 */File writename = new File("src/k/output.txt"); // 相对路径,如果没有则要建立一个新的output。txt文件writename.createNewFile(); // 创建新文件BufferedWriter out = new BufferedWriter(new FileWriter(writename));out.write(content); // \r\n即为换行out.flush(); // 把缓存区内容压入文件out.close(); // 最后记得关闭文件} catch (Exception e) {e.printStackTrace();}}public static void main(String[] args) {
/* List<float[]> ret = readTxt("src/k/t2.txt");long s=System.currentTimeMillis();KMeansRun kRun = new KMeansRun(5, ret);Set<Cluster> clusterSet = kRun.run();System.out.println("K-means聚类算法运行时间:"+(System.currentTimeMillis()-s)+"ms");System.out.println("单次迭代运行次数:" + kRun.getIterTimes());StringBuilder stringBuilder=new StringBuilder();for (Cluster cluster : clusterSet) {System.out.println("Mid_Point: "+cluster.getCenter()+" clusterId: "+cluster.getId()+" Points_num: "+cluster.getMembers().size());stringBuilder.append(cluster).append("\n");}writeTxt(stringBuilder.toString());*/List<float[]> ret = readTxt("src/k/t2.txt");XYSeries series = new XYSeries("xySeries");for (int x = 1; x < 20; x++) {KMeansRun kRun = new KMeansRun(x, ret);Set<Cluster> clusterSet = kRun.run();float y = 0;for (Cluster cluster : clusterSet){y+=cluster.getdis();}series.add(x, y);}XYSeriesCollection dataset = new XYSeriesCollection();dataset.addSeries(series);JFreeChart chart = ChartFactory.createXYLineChart("sum of the squared errors", // chart title"K", // x axis label"SSE", // y axis labeldataset, // dataPlotOrientation.VERTICAL,false, // include legendfalse, // tooltipsfalse // urls);ChartFrame frame = new ChartFrame("my picture", chart);frame.pack();frame.setVisible(true);frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);}
}
public class DistanceCompute {/*** 求欧式距离*/public double getEuclideanDis(Point p1, Point p2) {double count_dis = 0;float[] p1_local_array = p1.getlocalArray();float[] p2_local_array = p2.getlocalArray();if (p1_local_array.length != p2_local_array.length) {throw new IllegalArgumentException("length of array must be equal!");}for (int i = 0; i < p1_local_array.length; i++) {count_dis += Math.pow(p1_local_array[i] - p2_local_array[i], 2);}return Math.sqrt(count_dis);}
}
import java.util.*;public class KMeansRun {private int kNum; //簇的个数private int iterNum = 200; //迭代次数private int iterMaxTimes = 100000; //单次迭代最大运行次数private int iterRunTimes = 0; //单次迭代实际运行次数private float disDiff = (float) 0.01; //单次迭代终止条件,两次运行中类中心的距离差private List<float[]> original_data =null; //用于存放,原始数据集private static List<Point> pointList = null; //用于存放,原始数据集所构建的点集private DistanceCompute disC = new DistanceCompute();private int len = 0; //用于记录每个数据点的维度public KMeansRun(int k, List<float[]> original_data) {this.kNum = k;this.original_data = original_data;this.len = original_data.get(0).length;//检查规范check();//初始化点集。init();}/*** 检查规范*/private void check() {if (kNum == 0){throw new IllegalArgumentException("k must be the number > 0");}if (original_data == null){throw new IllegalArgumentException("program can't get real data");}}/*** 初始化数据集,把数组转化为Point类型。*/private void init() {pointList = new ArrayList<Point>();for (int i = 0, j = original_data.size(); i < j; i++){pointList.add(new Point(i, original_data.get(i)));}}/*** 随机选取中心点,构建成中心类。*/private Set<Cluster> chooseCenterCluster() {Set<Cluster> clusterSet = new HashSet<Cluster>();Random random = new Random();for (int id = 0; id < kNum; ) {Point point = pointList.get(random.nextInt(pointList.size()));// 用于标记是否已经选择过该数据。boolean flag =true;for (Cluster cluster : clusterSet) {if (cluster.getCenter().equals(point)) {flag = false;}}// 如果随机选取的点没有被选中过,则生成一个clusterif (flag) {Cluster cluster =new Cluster(id, point);clusterSet.add(cluster);id++;}}return clusterSet;}/*** 为每个点分配一个类!*/public void cluster(Set<Cluster> clusterSet){// 计算每个点到K个中心的距离,并且为每个点标记类别号for (Point point : pointList) {float min_dis = Integer.MAX_VALUE;for (Cluster cluster : clusterSet) {float tmp_dis = (float) Math.min(disC.getEuclideanDis(point, cluster.getCenter()), min_dis);if (tmp_dis != min_dis) {min_dis = tmp_dis;point.setClusterId(cluster.getId());point.setDist(min_dis);}}}// 新清除原来所有的类中成员。把所有的点,分别加入每个类别for (Cluster cluster : clusterSet) {cluster.getMembers().clear();for (Point point : pointList) {if (point.getClusterid()==cluster.getId()) {cluster.addPoint(point);}}}}/*** 计算每个类的中心位置!*/public boolean calculateCenter(Set<Cluster> clusterSet) {boolean ifNeedIter = false;for (Cluster cluster : clusterSet) {List<Point> point_list = cluster.getMembers();float[] sumAll =new float[len];// 所有点,对应各个维度进行求和for (int i = 0; i < len; i++) {for (int j = 0; j < point_list.size(); j++) {sumAll[i] += point_list.get(j).getlocalArray()[i];}}// 计算平均值for (int i = 0; i < sumAll.length; i++) {sumAll[i] = (float) sumAll[i]/point_list.size();}// 计算两个新、旧中心的距离,如果任意一个类中心移动的距离大于dis_diff则继续迭代。if(disC.getEuclideanDis(cluster.getCenter(), new Point(sumAll)) > disDiff){ifNeedIter = true;}// 设置新的类中心位置cluster.setCenter(new Point(sumAll));}return ifNeedIter;}/*** 运行 k-means*/public Set<Cluster> run() {Set<Cluster> clusterSet= chooseCenterCluster();boolean ifNeedIter = true;while (ifNeedIter) {cluster(clusterSet);ifNeedIter = calculateCenter(clusterSet);iterRunTimes ++ ;}return clusterSet;}/*** 返回实际运行次数*/public int getIterTimes() {return iterRunTimes;}}
public class Point {private float[] localArray;private int id;private int clusterId; // 标识属于哪个类中心。private float dist; // 标识和所属类中心的距离。public Point(int id, float[] localArray) {this.id = id;this.localArray = localArray;}public Point(float[] localArray) {this.id = -1; //表示不属于任意一个类this.localArray = localArray;}public float[] getlocalArray() {return localArray;}public int getId() {return id;}public void setClusterId(int clusterId) {this.clusterId = clusterId;}public int getClusterid() {return clusterId;}public float getDist() {return dist;}public void setDist(float dist) {this.dist = dist;}@Overridepublic String toString() {String result = "Point_id=" + id + " [";for (int i = 0; i < localArray.length; i++) {result += localArray[i] + " ";}return result.trim()+"] clusterId: "+clusterId;}@Overridepublic boolean equals(Object obj) {if (obj == null || getClass() != obj.getClass())return false;Point point = (Point) obj;if (point.localArray.length != localArray.length)return false;for (int i = 0; i < localArray.length; i++) {if (Float.compare(point.localArray[i], localArray[i]) != 0) {return false;}}return true;}@Overridepublic int hashCode() {float x = localArray[0];float y = localArray[localArray.length - 1];long temp = x != +0.0d ? Double.doubleToLongBits(x) : 0L;int result = (int) (temp ^ (temp >>> 32));temp = y != +0.0d ? Double.doubleToLongBits(y) : 0L;result = 31 * result + (int) (temp ^ (temp >>> 32));return result;}
}