机器学习二：感知器算法实现

川长思鸟来 2022-05-28 12:27 221阅读 0赞

本次也是用processing3.0+写的，其官方网站https://processing.org/，建议直接看reference的例子进行学习。

感知器算法用的是我们老师给的ppt，实现的是二维的感知器，为了方便看，实际上多维的也是一样的：

![1093219-20180102130252346-503273371.png][]

运行效果是：

![1093219-20180102130312221-1063830461.png][]

为了试验方便，我这是用了点击取点，键盘按一下t，大小写均可，下一个点的就是正例，按一下f，大小写均可，下一个点就是负例。

按s是开始进行学习度为1的迭代。结束会直接出直线，按2会出学习率为2的直线，迭代次数会打在程序底下，值是2.

代码仅供参考，请勿抄袭。转载请注明出处。

//blog:http://www.cnblogs.com/SweetBeens/p/8176764.html
    class Point{
      float x, y;
      int k;
      Point(float x1,float y1){
        x = x1; y = y1;
      }
    }
    int num = 500;
    int len = 0;
    float h=1;
    float r=0;
    Point [] points = new Point[num];
    int irit = 1000;
    float w1 = 0, w2 = 0, b = 0;
    //false=-1,true=1
    boolean type = true;
    //if one point wrong,then ,you need another irretate
    boolean flag = true;
    //one irretate
    void rewrite(){
      for(int i = 0; i < len; i++){
        //if points[i] wrong side
        float result=points[i].k*(points[i].x*w1+points[i].y*w2+b);
        if(result<=0){
          w1 = w1+h*points[i].k*points[i].x;
          w2 = w2+h*points[i].k*points[i].y;
          b = b + h * points[i].k*r*r ;
          print(b," ");
          //w1=w1/w2;
         // w2=1;
          //b=b/w2;
          flag=true;
        }
      }
      }
    //calculate R,check out in ppt 
    void R(){
      float max=0;
      for(int i=0;i<len;i++){
        if(abs(points[i].x)>max)
        max=abs(points[i].x);
        if(abs(points[i].y)>max)
        max=abs(points[i].y);
      }
      r=max;
      println("max ",max);
    }
    void mousePressed(){
      Point p = new Point(mouseX,mouseY);
      if(type){
      p.k = 1;
      fill(255);
      }
      else{
      p.k = -1;
      fill(0);
      }
      rect(mouseX,mouseY,5,5);
      points[len] = p;
      len++;
    }
    void keyPressed(){
      int i=0;
      float y1=0,y2=0;
      if(key == 'T' || key == 't')
      type = true;
      else if(key == 'F' || key == 'f')
      type = false;
      else if(key == 's' || key == 'S')
      {
        
        R();
        while(i<irit&&flag==true){
          i++;
        flag=false;
        rewrite();
      //  println("w",w1," ",w2,"b",b);
         y1 = -b/w2;
        y2 = (-b-w1*width) / w2;
        //line(0,10,width,480);
       
        }
        println(y1," ",y2);
        println("w1,w2,b "+w1,w2,b);
         line(0,y1,width,y2);
      }
      else if(key == '2'){
        h = 0.2;
        w1 = 0;
        w2 = 0;
        b = 0;
        flag=true;
        i=0;
        while(i<irit&&flag==true){
          i++;
        flag=false;
        rewrite();
      //  println("w",w1," ",w2,"b",b);
         y1 = -b/w2;
        y2 = (-b-w1*width) / w2;
        //line(0,10,width,480);
       
        }
        println(y1," ",y2);
        println("w1,w2,b "+w1,w2,b);
         line(0,y1,width,y2);
      
      }
      println("i ",i);
    }
    void setup(){
      size(500,500);
      background(255);
    }
    void draw(){
    }

[1093219-20180102130252346-503273371.png]: /images/20220528/4572d97aa4d64d3e8402aa0a866e84f6.png
[1093219-20180102130312221-1063830461.png]: /images/20220528/d5593aed452f4ae8911e61f16a156cdd.png