Custom approximation function
I would like to have an approximation function in which we can access all the information from the points instead of just the y values. This allows me to not only decide how to group but also an ability to capture information from all the points into the grouped point.
As of the next release, we have implemented a hook for getting the raw data for data grouping. See http://jsfiddle.net/xfLLr03a/.
Juuso Palander commented
This would enable calculating weighted average also, which is currently lacking as far as I know.