I want to produce a moving average for a time series using the JFreeChart MovingAverage.createMovingAverage method in org.jfree.data.time.MovingAverage. But my data is a countdown, i.e. the values for the time parameter are counting down. So when I apply this moving average function it produces a moving average counting up not down, i.e. includes N values with time lower than the current time, I would like to take the N values with time higher than the current time.

Any ideas how I can achieve this without rewriting my own moving average method?