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

InputArray does a good job here. You can simply call

cv::Mat mean_;
cv::reduce(points, mean_, 01, CV_REDUCE_AVG);
// convert from Mat to Point - there may be even a simpler conversion, 
// but I do not know about it.
cv::Point2f mean(mean_.at(0,0), mean_.at(0,1)); 

Details:

In the newer OpenCV versions, the InputArray data type is introduced. This way, one can send as parameters to an OpenCV function either matrices (cv::Mat) either vectors. A vector will be interpreted as a float matrix with three channels, one row, and the number of columns equal to the vector size. Because no data is copied, this transparent conversion is very fast.

The advantage is that you can work with whatever data type fits better in your app, while you can still use OpenCV functions to ease mathematical operations on it.