java - 使用Java的K均值聚类

Question

我在Internet上找到了以下代码。我认为类型转换存在问题。
我试图解决其中的一些问题，但仍然很少有人可以解决。

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

 public class Cluster {

    public List points;
    public Point centroid;
    public int id;

    //Creates a new Cluster
    public Cluster(int id) {
        this.id = id;
        this.points = new ArrayList();
        this.centroid = null;
    }

    public List getPoints() {
        return points;
    }

    public void addPoint(Point point) {
        points.add(point);
    }

    public void setPoints(List points) {
        this.points = points;
    }

    public Point getCentroid() {
        return centroid;
    }

    public void setCentroid(Point centroid) {
        this.centroid = centroid;
    }

    public int getId() {
        return id;
    }

    public void clear() {
        points.clear();
    }

    public void plotCluster() {
        System.out.println("[Cluster: " + id+"]");
        System.out.println("[Centroid: " + centroid + "]");
        System.out.println("[Points: \n");
        for(Point p : points) {
            System.out.println(p);
        }
        System.out.println("]");
    }

}

public class Point {

    private double x = 0;
    private double y = 0;
    private int cluster_number = 0;

    public Point(double x, double y)
    {
        this.setX(x);
        this.setY(y);
    }

    public void setX(double x) {
        this.x = x;
    }

    public double getX()  {
        return this.x;
    }

    public void setY(double y) {
        this.y = y;
    }

    public double getY() {
        return this.y;
    }

    public void setCluster(int n) {
        this.cluster_number = n;
    }

    public int getCluster() {
        return this.cluster_number;
    }

    //Calculates the distance between two points.
    protected static double distance(Point p, Point centroid) {
        return Math.sqrt(Math.pow((centroid.getY() - p.getY()), 2) + Math.pow((centroid.getX() - p.getX()), 2));
    }

    //Creates random point
    protected static Point createRandomPoint(int min, int max) {
        Random r = new Random();
        double x = min + (max - min) * r.nextDouble();
        double y = min + (max - min) * r.nextDouble();
        return new Point(x,y);
    }

    protected static List createRandomPoints(int min, int max, int number) {
        List points = new ArrayList(number);
        for(int i = 0; i < number; i++) {
            points.add(createRandomPoint(min,max));
        }
        return points;
    }

    public String toString() {
        return "("+x+","+y+")";
    }
}
public class KMeans {

    //Number of Clusters. This metric should be related to the number of points
    private int NUM_CLUSTERS = 3;    
    //Number of Points
    private int NUM_POINTS = 15;
    //Min and Max X and Y
    private static final int MIN_COORDINATE = 0;
    private static final int MAX_COORDINATE = 10;

    private List points;
    private List clusters;

    public KMeans() {
        this.points = new ArrayList();
        this.clusters = new ArrayList();        
    }

    public static void main(String[] args) {

        KMeans kmeans = new KMeans();
        kmeans.init();
        kmeans.calculate();
    }

    //Initializes the process
    public void init() {
        //Create Points
        points = Point.createRandomPoints(MIN_COORDINATE,MAX_COORDINATE,NUM_POINTS);

        //Create Clusters
        //Set Random Centroids
        for (int i = 0; i < NUM_CLUSTERS; i++) {
            Cluster cluster = new Cluster(i);
            Point centroid = Point.createRandomPoint(MIN_COORDINATE,MAX_COORDINATE);
            cluster.setCentroid(centroid);
            clusters.add(cluster);
        }

        //Print Initial state
        plotClusters();
    }

    private void plotClusters() {
        for (int i = 0; i < NUM_CLUSTERS; i++) {
            Cluster c = clusters.get(i);
            c.plotCluster();
        }
    }

    //The process to calculate the K Means, with iterating method.
    public void calculate() {
        boolean finish = false;
        int iteration = 0;

        // Add in new data, one at a time, recalculating centroids with each new one. 
        while(!finish) {
            //Clear cluster state
            clearClusters();

            List lastCentroids = getCentroids();

            //Assign points to the closer cluster
            assignCluster();

            //Calculate new centroids.
            calculateCentroids();

            iteration++;

            List currentCentroids = getCentroids();

            //Calculates total distance between new and old Centroids
            double distance = 0;
            for(int i = 0; i < lastCentroids.size(); i++) {
                distance += Point.distance(lastCentroids.get(i),currentCentroids.get(i));
            }
            System.out.println("#################");
            System.out.println("Iteration: " + iteration);
            System.out.println("Centroid distances: " + distance);
            plotClusters();

            if(distance == 0) {
                finish = true;
            }
        }
    }

    private void clearClusters() {
        for(Cluster cluster : clusters) {
            cluster.clear();
        }
    }

    private List getCentroids() {
        List centroids = new ArrayList(NUM_CLUSTERS);
        for(Cluster cluster : clusters) {
            Point aux = cluster.getCentroid();
            Point point = new Point(aux.getX(),aux.getY());
            centroids.add(point);
        }
        return centroids;
    }

    private void assignCluster() {
        double max = Double.MAX_VALUE;
        double min = max; 
        int cluster = 0;                 
        double distance = 0.0; 

        for(Point point : points) {
            min = max;
            for(int i = 0; i < NUM_CLUSTERS; i++) {
                Cluster c = clusters.get(i);
                distance = Point.distance(point, c.getCentroid());
                if(distance < min){
                    min = distance;
                    cluster = i;
                }
            }
            point.setCluster(cluster);
            clusters.get(cluster).addPoint(point);
        }
    }

    private void calculateCentroids() {
        for(Cluster cluster : clusters) {
            double sumX = 0;
            double sumY = 0;
            List list = cluster.getPoints();
            int n_points = list.size();

            for(Point point : list) {
                sumX += point.getX();
                sumY += point.getY();
            }

            Point centroid = cluster.getCentroid();
            if(n_points > 0) {
                double newX = sumX / n_points;
                double newY = sumY / n_points;
                centroid.setX(newX);
                centroid.setY(newY);
            }
        }
    }
}

我得到了以下错误。如何解决它们:

java:45: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
            clusters.add(cluster);
                        ^
  where E is a type-variable:
    E extends Object declared in interface List
/tmp/java_kmNqUn/KMeans.java:54: error: incompatible types: Object cannot be converted to Cluster
            Cluster c = clusters.get(i);
                                    ^
/tmp/java_kmNqUn/KMeans.java:84: error: incompatible types: Object cannot be converted to Point
                distance += Point.distance(lastCentroids.get(i),currentCentroids.get(i));
                                                            ^
/tmp/java_kmNqUn/KMeans.java:98: error: incompatible types: Object cannot be converted to Cluster
        for(Cluster cluster : clusters) {
                              ^
/tmp/java_kmNqUn/KMeans.java:105: error: incompatible types: Object cannot be converted to Cluster
        for(Cluster cluster : clusters) {
                              ^
/tmp/java_kmNqUn/KMeans.java:108: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
            centroids.add(point);
                         ^
  where E is a type-variable:
    E extends Object declared in interface List
/tmp/java_kmNqUn/KMeans.java:119: error: incompatible types: Object cannot be converted to Point
        for(Point point : points) {
                          ^
/tmp/java_kmNqUn/KMeans.java:122: error: incompatible types: Object cannot be converted to Cluster
                Cluster c = clusters.get(i);
                                        ^
/tmp/java_kmNqUn/KMeans.java:130: error: cannot find symbol
            clusters.get(cluster).addPoint(point);
                                 ^
  symbol:   method addPoint(Point)
  location: class Object
/tmp/java_kmNqUn/KMeans.java:135: error: incompatible types: Object cannot be converted to Cluster
        for(Cluster cluster : clusters) {
                              ^
/tmp/java_kmNqUn/KMeans.java:141: error: incompatible types: Object cannot be converted to Point
            for(Point point : list) {
                              ^
/tmp/java_kmNqUn/Point.java:61: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
            points.add(createRandomPoint(min,max));
                      ^
  where E is a type-variable:
    E extends Object declared in interface List
/tmp/java_kmNqUn/Cluster.java:27: warning: [unchecked] unchecked call to add(E) as a member of the raw type List
        points.add(point);
                  ^
  where E is a type-variable:
    E extends Object declared in interface List
/tmp/java_kmNqUn/Cluster.java:54: error: incompatible types: Object cannot be converted to Point
        for(Point p : points) {
                      ^
Note: Some messages have been simplified; recompile with -Xdiags:verbose to get full output
10 errors
4 warnings*

请指导我...

Answer 1

您应该避免使用没有任何类型参数的List类型。您应该改用List<SomeType>(用相关类型替换SomeType)。