def __pixelVelocity(self):
        ts = self
        if len(ts) < 2:
            return (0,0)
        dx = ts[-1].x - ts[-2].x
        dy = ts[-1].y - ts[-2].y
        return (dx, dy)
**SUMMARY**
dataset/ETHPy150Open sightmachine/SimpleCV/SimpleCV/Tracking/TrackSet.py/TrackSet.__pixelVelocity