point.java

JAVA 本程序所实现的功能为对数据进行无监督的学习

import java.util.Vector;
/**********************************************************
* A public class the stores the representation of a single 
* data point in the database. Currently it stores 2D data.
*/
public class Point
{
    double x; // store the x-coordinate
    double y; // store the y-coordinate
    
    /** Constructor
      * Creates a new Point with the given coordinates
     * @param xVal Value of x coordinate
     * @param yVal Value of y coordinate
    */
    public Point(double xVal, double yVal)
    {
        x = xVal;
        y = yVal;
    }
    
    /** Method to return the Euclidean distance between this point and the given point
     * @param p The point to measure the distance to
     * @return The euclidean distance
     */
    public double EuclideanDistance(Point p)
    {
        return Math.sqrt((p.x - x)*(p.x - x) + (p.y - y)*(p.y -y));
    }
    
    /** Returns the value of the x-coordinate of this point
     * @return The value of x coordinate
     */
    public double xVal()
    {
        return x;
    }
    
    /** Returns the value of the y-coordinate of this point
     * @return The value of y coordinate
     */
    public double yVal()
    {
        return y;
    }
    
    /** Method to calculate the mean point of a given vector of points
     * @param clust the Vector of points to find the mean of 
     * @return A point which is the mean of the given vector. Returns (0,0)
     * if the Vector is empty
     */
    static public Point mean(Vector clust)
    {
        double xsum=0.0;
        double ysum=0.0;
        int size = clust.size();
        
        if (size == 0)
            return new Point (0,0); // no points in Vector, return 0,0
        // calcuate the sum of x and y coordinates
        for (int j= 0; j < size; j++)        
        {
            Point p = (Point) clust.elementAt(j);
            xsum += p.x;
            ysum += p.y;
        }
        return new Point(xsum/size,ysum/size);
    }
    
    /** Returns a string representation of the point
     * @return x and y coordinates in a string
     */
    public String toString()
    {
        return x + " " + y;
    }
    
    /** Method to return the value of the n-th requested dimension
     * @param index The dimension to return the value of. Must be 0 or 1
     * @return The value of the requested dimension
    */
    public double value(int index) {
        if (index == 0)
            return x;
        else
            return y;
    }
    
    /** Method to return the number of dimensions in the current point 
     * @param The number of dimensions. Currently is always 2
     */
    public static int nAttribs() {
        return 2;
    }
}