Java实现的KNN算法示例

package KNN;
/**
 * 点的坐标 x 、y
 * @author Administrator
 *
 */
public class PointBean {
int x;
int y;
public int getX() {
  return x;
}
public void setX(int x) {
  this.x = x;
}
public int getY() {
  return y;
}
public void setY(int y) {
  this.y = y;
}
public PointBean(int x, int y) {
  super();
  this.x = x;
  this.y = y;
}
public PointBean() {
  super();
}
@Override
public String toString() {
  return "PointBean [x=" + x + ", y=" + y + "]";
}
}

package KNN;
import java.util.ArrayList;
/**
 * KNN实现的方法
 * @author Administrator
 *
 */
public class KnnMain {
  public double getPointLength(ArrayList<PointBean> list,PointBean bb){
    int b_x=bb.getX();
    int b_y=bb.getY();
    double temp=(b_x -list.get(0).getX())*(b_x -list.get(0).getX())+
        (b_y -list.get(0).getY())*(b_y -list.get(0).getY());
    // 找出最小的距离
    for(int i=1;i<list.size();i++){
      if(temp<((b_x -list.get(i).getX())*(b_x -list.get(i).getX())+
          (b_y -list.get(i).getY())*(b_y -list.get(i).getY()))){
        temp=(b_x -list.get(i).getX())*(b_x -list.get(i).getX())+
            (b_y -list.get(i).getY())*(b_y -list.get(i).getY());
      }
    }
    return Math.sqrt(temp);
  }
  /**
   * 获取长度，找出最小的一个进行归类
   * @param list1
   * @param list2
   * @param list3
   * @param bb
   */
  public void getContent(ArrayList<PointBean> list1,ArrayList<PointBean> list2,
      ArrayList<PointBean> list3,PointBean bb){
    double A=getPointLength(list1,bb);
    double B=getPointLength(list2,bb);
    double C=getPointLength(list3,bb);
    //做出比较
    if(A>B){
      if(B>C){
        System.out.println("这个点:"+bb.getX()+" , "+bb.getY()+" " +"属于C");
      }else {
        System.out.println("这个点:"+bb.getX()+" , "+bb.getY()+" " +"属于B");
      }
    }else {
      if(A>C){
        System.out.println("这个点:"+bb.getX()+" , "+bb.getY()+" " +"属于C");
      }else {
        System.out.println("这个点:"+bb.getX()+" , "+bb.getY()+" " +"属于A");
      }
    }
  }
}

package KNN;
import java.util.ArrayList;
/*
 * 主函数 KNN
 */
public class TestJava {
  static ArrayList< PointBean> listA;
  static ArrayList< PointBean> listB;
  static ArrayList< PointBean> listC;
  static ArrayList< PointBean> listD;
  public static void main(String[] args) {
    //创佳Arraylist
    listA=new ArrayList<PointBean>();
    listB=new ArrayList<PointBean>();
    listC=new ArrayList<PointBean>();
    listD=new ArrayList<PointBean>();
    //写入数据
    setDate();
    getTestResult();
  }
  /**
   * 得到结果
   */
  private static void getTestResult() {
    //创建对象
    KnnMain km=new KnnMain();
    for(int i=0;i<listD.size();i++){
      km.getContent(listA, listB, listC, listD.get(i));
    }
  }
  /**
   * 写入数据
   */
  private static void setDate() {
    //A的坐标点
    int A_x[]={1,1,2,2,1};
    int A_y[]={0,1,1,0,2};
    //B的坐标点
    int B_x[]={2,3,3,3,4};
    int B_y[]={4,4,3,2,3};
    //C的坐标点
    int C_x[]={4,5,5,6,6};
    int C_y[]={1,2,0,2,1};
    // 测试数据
    //B的坐标点
    int D_x[]={3,3,3,0,5};
    int D_y[]={0,1,5,0,1};
    //
    PointBean bA;
    for(int i=0;i<5;i++){
      bA=new PointBean(A_x[i], A_y[i]);
      listA.add(bA);
    }
    //
    PointBean bB ;
    for(int i=0;i<5;i++){
      bB=new PointBean(B_x[i], B_y[i]);
      listB.add(bB);
    }
    //
    PointBean bC ;
    for(int i=0;i<5;i++){
      bC=new PointBean(C_x[i], C_y[i]);
      listC.add(bC);
    }
    //
    PointBean bD ;
    for(int i=0;i<5;i++){
      bD=new PointBean(D_x[i], D_y[i]);
      listD.add(bD);
    }
  }
}