Calculate mean for vector of points

Question

I have a vector of a 2-dimensional points in OpenCV

std::vector points;

I would like to calculate the mean values for x and

Answer 1

Since OpenCV's Point_ already defines operator+, this should be fairly simple. First we sum the values:

cv::Point2f zero(0.0f, 0.0f);

cv::Point2f sum  = std::accumulate(points.begin(), points.end(), zero);

Then we divide to get the average:

Point2f mean_point(sum.x / points.size(), sum.y / points.size());

...or we could use Point_'s operator*:

Point2f mean_point(sum * (1.0f / points.size()));

Unfortunately, at least as far as I can see, Point_ doesn't define operator /, so we need to multiply by the inverse instead of dividing by the size.