This is the new implementation of the filters' windowing scheme. Now, specifying 4 points and 6 hours will guarantee that at least 4 points are in the window AND 6 hours, otherwise it returns unsuccessfully. The run time penalty is ~4% compared to the previous implementation. Since it first builds the window specifications (start and end index), it is possible to directly call this window specification, skipping the building of a vector of pointers. For the MeanAvg filter, this makes the run time penalty go down to 3.3% on a 6 hours window (with hourly data).