四月的筆記

先計算重心: meanX 和 meanY

 

Slope = (sumXY - n * meanX * meanY) / (sumX2 - n * meanX * meanX);

Shift = meanY - Slope * meanX;

 

#include <iostream>

void Line_Slope(double* X_tmp, double* Y_tmp , int Count_tmp, double & slope , double & shift )
{
    double sum_xx = 0;
    double sum_xy = 0;
    double mean_x = 0;
    double mean_y = 0;

    for (int i = 0; i < Count_tmp; i++) 
    {
        sum_xx = sum_xx + (*(X_tmp + i)) * (*(X_tmp + i));
        sum_xy = sum_xy + (*(X_tmp + i)) * (*(Y_tmp + i));
        mean_x = mean_x + (*(X_tmp + i)) ;
        mean_y = mean_y + (*(Y_tmp + i));
    }

    mean_x = mean_x / (double)Count_tmp;
    mean_y = mean_y / (double)Count_tmp;

    slope = (sum_xy - Count_tmp * mean_x * mean_y) / (sum_xx - Count_tmp * mean_x * mean_x);
    shift = mean_y - slope * mean_x;
}



int main()
{
    double X_array[] = { 148,206,395,493,521,617,767,870,971 };
    double Y_array[] = { 356,597,768,946,1140,1396,1570,1706,1967 };
    int Count = 9;
    double slope = 1;
    double shift = 0;

    Line_Slope(X_array, Y_array, Count, slope, shift);

    std::cout << "test: " << slope << " " << shift << "\n";
    std::cin.get();
}

 

---

使用 vector  時

void Line_Slope(const std::vector < double > &X_tmp, const std::vector < double > &Y_tmp, double& slope, double& Intercept)
{

    int Count_tmp = X_tmp.size();

    double sum_xx = 0;
    double sum_xy = 0;
    double mean_x = 0;
    double mean_y = 0;

    for (int i = 0; i < Count_tmp; i++)
    {
        sum_xx = sum_xx + X_tmp[i] * X_tmp[i];
        sum_xy = sum_xy + X_tmp[i] * Y_tmp[i];
        mean_x = mean_x + X_tmp[i];
        mean_y = mean_y + Y_tmp[i];
    }

    mean_x = mean_x / (double)Count_tmp;
    mean_y = mean_y / (double)Count_tmp;

    slope = (sum_xy - Count_tmp * mean_x * mean_y) / (sum_xx - Count_tmp * mean_x * mean_x);
    Intercept = mean_y - slope * mean_x;

}


int main()
{
	std::vector < double >  X_array = { 148,206,395,493,521,617,767,870,971 };
 	std::vector < double >  Y_array = { 356,597,768,946,1140,1396,1570,1706,1967 };
 
 	double slope = 1;
 	double shift = 0;

 	Line_Slope(X_array, Y_array, slope, shift);

 	std::cout << "test: " << slope << " " << shift << "\n";
 	std::cin.get();
}

 

 

---

影像上用 unsigned char* 時

切記只有 0~255

#include <iostream>

void Line_Slope(unsigned char* X_tmp, unsigned char* Y_tmp , int Count_tmp, double & slope , double & shift )
{
    float sum_xx = 0;
    float sum_xy = 0;
    float mean_x = 0;
    float mean_y = 0;

    for (int i = 0; i < Count_tmp; i++) 
    {
        sum_xx = sum_xx + ((float)(*(X_tmp + i)) * (float)(*(X_tmp + i)));
        sum_xy = sum_xy + ((float)(*(X_tmp + i)) * (float)(*(Y_tmp + i)));
        mean_x = mean_x + ((float)(*(X_tmp + i)));
        mean_y = mean_y + ((float)(*(Y_tmp + i)));
    }

   
    mean_x = mean_x / (float)Count_tmp;
    mean_y = mean_y / (float)Count_tmp;


    slope = (sum_xy - Count_tmp * mean_x * mean_y) / (sum_xx - Count_tmp * mean_x * mean_x);
    shift = mean_y - slope * mean_x;


}

int main()
{
    unsigned char X_array[] = { 14,20,39,49,52,61,76,87,97 };
    unsigned char Y_array[] = { 35,59,76,94,114,139,157,170,196 };
    int Count = 9;
    double slope = 1;
    double shift = 0;


    Line_Slope(X_array, Y_array, Count, slope, shift);




    std::cout << "test: " << slope << " " << shift << "\n";

    for (int i = 0; i < Count; i++)
    {
        std::cout << (double)(*(X_array + i)) << " " << (double)(*(Y_array + i)) << std::endl;
    }



    std::cin.get();
}