OpenCV C++: Sorting contours by their contourArea

Question

How can I sort contours by the size of their contour areas? And how can I get the biggest/smallest one?

Answer 1

Just give a solution using the lambda function if C++11 is available.

    sort(contours.begin(), contours.end(), [](const vector& c1, const vector& c2){
    return contourArea(c1, false) < contourArea(c2, false);
});

Then you can access contours[0] to get the contour with the smallest area and contours[contours.size()-1] to get the one with the largest area because the contours are sorted in ascending order.