归并排序向量 C++ OpenCV

Question

我需要为不存在的点订购一个坐标向量，但要订购通过指向矩阵中的坐标获得的值。例如

vector < Point > // v has two coordinates within
Mat D ( 2,2 ) ;
int a = v [ 0 ] .x ;
int b = v [ 0 ] .y ;
int c = v [ 1 ] .x ;
int d = v [ 1 ] .y ;
if ( D.at < int > ( a, b) <  D.at<int> ( c, d ) )
// Sort in ascending order

我尝试使用合并排序并进行适当的更改来搜索“坐标值”：

void work::merge(vector<cv::Point>& Q1, int low, int high, int mid, Mat & Densita)
{
    cout << "merge" << endl;
    int i, j, k;
    vector<cv::Point> c;
    i = low;
    k = low;
    j = mid + 1;
    while (i <= mid && j <= high)
    {
        cout << "-" << endl;
        int X = Q1[i].x;
        int Y = Q1[i].y;
        int W = Q1[j].x;
        int Q = Q1[j].y;
        int a = Densita.at<int>(X, Y);
        int b = Densita.at<int>(W,Q);
        if (a < b)
        {   
            cout << "min" << endl;
            c.push_back(cv::Point(X, Y));
            k++;
            i++;
        }
        else
        {
            cout << "max" << endl;
            c.push_back(cv::Point(W, Q));
            k++;
            j++;
        }
    }
    while (i <= mid)
    {
        cout << "D" << endl;
        int X = Q1[i].x;
        int Y = Q1[i].y;
        c.push_back(cv::Point(X, Y));
        k++;
        i++;
    }
    while (j <= high)
    {
        cout << "§" << endl;
        int W = Q1[j].x;
        int Q = Q1[j].y;
        c.push_back(cv::Point(W, Q));
        k++;
        j++;
    }
    for (k = low; k < high; k++)
    {
        cout << "***" << endl;
        Q1.at(k) = c.at(k);
    }

}


void work::mergesort(vector<cv::Point>& Q1, int low, int high, Mat & Densita)
{   
    cout << "RichiamoMergesort" << endl;
    int mid;
    if (low < high)
    {
        mid = (low + high) / 2;
        mergesort(Q1, low, mid, Densita);
        mergesort(Q1, mid + 1, high, Densita);
        merge(Q1, low, high, mid, Densita);
    }
}

但在进入合并后他工作了一点然后返回给我这个错误

invalid vector<T> subscript ------>with vs2015

为什么？我究竟做错了什么？怎么解决？

Answer 1

您应该通过为 std::sort 函数提供自定义比较器来实现此目的，而不是重写它。大致如下：

struct PointCmp {  
    Mat* d;
    PointCmp(Mat* _d): d(_d) {} 

    inline bool operator() (const Point& p1, const Point& p2) {
        return d->at<int>(p1.x, p1.y) < d->at<int>(p2.x, p2.y);
    }
};

int main() {
   // other stuff
   std::vector<Point> v;    
   Mat d(2, 2);
   std::sort(v.begin(), v.end(), PointCmp(&d));
}

归并排序向量 C++ OpenCV

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