sub2Ind matlab to c++/opencv conversion - c++

Question

I'm trying to create this code in c++/ I'm using openCV but don't have to.
wi = size(Gr, 2);
he = size(Gr, 1);
cropFactor = 0.10;
[x, y] = meshgrid( round(cropFactor * wi):round( (1-cropFactor)*wi ), round(cropFactor * he):round((1-cropFactor)*he) );
xy = sub2ind(size(Gr), y(:), x(:));
here is what I have so far
int width = dst.cols;
int height = dst.rows;
double cropFactor = 0.10;
cv::Mat1i X,Y;
Utilities::Meshgrid(Utilities::MatlabRound(cropFactor * width), Utilities::MatlabRound((1 - cropFactor) * width), Utilities::MatlabRound(cropFactor * height), Utilities::MatlabRound((1-cropFactor) * height),X, Y);
Utilities::Sub2Ind(width, height, X, Y);
round() function
int Utilities::MatlabRound(double numberToRound)
{
return floor( numberToRound + 0.5);
}
this is my meshgrid() function it works as expected
void Utilities::Meshgrid(int startX, int endX, int startY, int endY, cv::Mat1i &X, cv::Mat1i & Y)
{
std::vector<int> vec_x, vec_y;
for (int i = startX; i <= endX; i++)
{
vec_x.push_back(i);
}
for (int i = startY; i <= endY; i++)
{
vec_y.push_back(i);
}
cv::Mat x = cv::Mat(vec_x);
cv::Mat y = cv::Mat(vec_y);
cv::repeat(x.reshape(1,1), y.total(), 1, X);
cv::repeat(y.reshape(1,1).t(), 1, x.total(), Y);
}
however i'm having trouble understanding what are subscripts and how to implement Sub2Ind function
Can you please explain?
update I have implemented sub2ind please see my answer

Answer 1

I have implemented sub2Ind for 2D matrix
it is tested and work fine
cv::Mat Utilities::Sub2Ind(int width, int height, cv::Mat X, cv::Mat Y)
{
/*sub2ind(size(a), rowsub, colsub)
sub2ind(size(a), 2 , 3 ) = 6
a = 1 2 3 ;
4 5 6
rowsub + colsub-1 * numberof rows in matrix*/
std::vector<int> index;
cv::transpose(Y,Y);
cv::MatConstIterator_<int> iterX = X.begin<int>(), it_endX = X.end<int>();
cv::MatConstIterator_<int> iterY = Y.begin<int>(), it_endY = Y.end<int>();
for (int j = 0; j < X.cols; ++j,++iterX)
{
//running on each col of y matrix
for (int i =0 ;i < Y.cols; ++i,++iterY )
{
int rowsub = *iterY;
int colsub = *iterX;
int res = rowsub + ((colsub-1)*height);
index.push_back(res);
}
int x = 5;
}
cv::Mat M(index) ;
return M;
}