I have a std::vector<cv::Mat1f> mat, where each element is a row matrix. If you wander why, look here.
The only solution that came to my mind is:
cv::Mat1f final;
for(int i=0; i<mat.rows; i++){
final.push_back( mat[i].row(0) );
}
final.reshape(1,1);
Is there any more efficient solution for this?
you could still preallocate it, and copy rows, which would shave off the cost for subsequential allocations triggered from the push_back():
Mat final(mat.size(), mat[0].cols, CV_32F);
for(size_t i=0; i<mat.size(); i++){
mat[i].copyTo(final.row(i));
}
final.reshape(1,1);
also look at hconcat() / vconcat(), though i doubt, that they are cheaper.
I thought that push_back was going to be just some operation involving smart pointers
oh, you were wrong about that. remember, that cv::Mat has continuous data storage, (it's not a vector of pointers), so each time you call push_back(), it has todo:
Asked: 2017-04-04 07:02:20 -0600
Seen: 1,223 times
Last updated: Apr 04 '17
mat.size(), notmat.rows, right ?