求解线性回归方程

忘是亡心i 2022-11-29 05:45 221阅读 0赞

#### 代码 ####

/**************************************************************************
    
    Copyright: none
    
    Author: YuanHao Liu
    
    Date:2019-09-14
    
    Description:Solving Linear Regression Equation
    
    **************************************************************************/
    
    #include <iostream>
    #include <fstream>
    #include <cstdio>
    #include <cmath>
    #include <string>
    #include <stdlib.h>
    
    using namespace std;
    
    double x[5000],y[5000];
    int n;
    
    double lineFit()
    {
        
        double aver_x=0,aver_y=0;
        double lxx=0,lyy=0,lxy=0;
        for(int i=0;i<n;++i)
        {
        
            aver_x+=x[i]/n;
            aver_y+=y[i]/n;
        }
        for(int i=0;i<n;++i)
        {
        
            lxx+=(x[i]-aver_x)*(x[i]-aver_x);
            lxy+=(x[i]-aver_x)*(y[i]-aver_y);
            lyy+=(y[i]-aver_y)*(y[i]-aver_y);
        }
        cout<<endl;
        cout<<"y=a*x+b"<<endl;
        cout<<"a="<<lxy/lxx<<endl;
        cout<<"b="<<aver_y-lxy*aver_x/lxx<<endl;
        return (lxy/sqrt(lxx*lyy));
    }
    
    int main()
    {
        
        // 输入文件路径
        cout<<"输入文件x:";
        string in_file_path;
        cin>>in_file_path;
    
        // 打开文件
        ifstream infile;
        infile.open(in_file_path.data(),ios::in);
    
        // 判断是否打开成功
        if(!infile.is_open())
        {
        
            // 若打开失败，终止程序并给出警告信息。
            cout<<"open file is error"<<endl;
            exit(1);
        }
        else
        {
        
            cout<<"file open success"<<endl;
        }
    
        // 读取数据x
        int i=0;
        while(infile.good())
        {
        
    
            infile>>x[i++];
        }
    
        // 测试读取数据
        for(int i=0;i<10;++i)
        {
        
            cout<<x[i]<<endl;
        }
        cout<<"总共"<<i<<"个x数据."<<endl;
    
        // 关闭文件
        infile.close();
    
    
    
        // 重复上述操作，读取数据y.
        cout<<"输入文件y:";
        cin>>in_file_path;
    
        infile.open(in_file_path.data(),ios::in);
        if(infile.is_open())
        {
        
            cout<<"file open success"<<endl;
        }
        else
        {
        
            cout<<"file open if error"<<endl;
            exit(1);
        }
    
        i=0;
        while(infile.good())
        {
        
            infile>>y[i++];
        }
        n=i;
        for(int i=0;i<10;++i)
        {
        
            cout<<y[i]<<endl;
        }
        cout<<"total y:"<<i<<endl;
    
        infile.close();
    
        double r=lineFit();
        cout<<"线性拟合程度:"<<r<<endl;
    
    
        return 0;
    }