贝叶斯决策 分类器

   

    

     

      

     
     

      

       x=[-3.9847  -3.5549 -1.2401  -0.9780 -0.7932  -2.8531 -2.7605  -3.7287 -2.5414  -2.2692 -3.4549  -3.0752 -3.9934  2.8792  -0.97800.7932  1.1882 3.0682  -1.5799 -1.4885  -0.7431 -0.4221  -1.1186  4.2532];
      
     
    

     

      

     
     

      

       pw1=0.9;pw2=0.1;%两类的先验概率，可以从历史数据中获得
      
     
    

     

      

     
     

      

       e1=-2;a1=0.5;%假设似然函数满足正态分布，均值为-2，方差为0.5
      
     
    

     

      

     
     

      

       e2=2;a2=2;
      
     
    

     

      

     
     

      

       m=numel(x) %得到待测细胞个数
      
     
    

     

      

     
     

      

       pw1_x=zeros(1,m); %存放对w1的后验概率矩阵
      
     
    

     

      

     
     

      

       pw2_x=zeros(1,m); %存放对w2的后验概率矩阵
      
     
    

     

      

     
     

      

       result=zeros(1,m);%存放比较结果矩阵
      
     
    

     

      

     
     

      
 
      
     
    

     

      

     
     

      

       for i=1:m
      
     
    

     

      

     
     

      

       %计算在w1下的后验概率
      
     
    

     

      

     
     

      

       pw1_x(i)=(pw1*normpdf(x(i),e1,a1))/(pw1*normpdf(x(i),e1,a1)+pw2*normpdf(x(i),e2,a2));
      
     
    

     

      

     
     

      

       pw2_x(i)=(pw2*normpdf(x(i),e1,a1))/(pw1*normpdf(x(i),e1,a1)+pw2*no