moving_average.r2py

"""
<Program Name>
  moving_average.r2py

<Purpose>
  This is a script for moving average filter to filter out 
  the raw acceleration data. Introducing an preset maximum 
  sample interval to avoid device lag.
"""




# output: y = sum(x[i])/length, i in range (0, window_size)
# minimum window size is 4
# the delay = window_size/2
class MovingAverageFilter:
	def __init__(self, moving_average_sample, current_time, threshold):
		self.mag_list = []
		self.window_size = moving_average_sample
		self.last_time = current_time
		self.threshold = threshold



	def moving_average_filter(self, data, current_time):
		# avoid device lag
		# different sampling time interval will reduce the filter's accuracy
		if current_time - self.last_time > self.threshold:
			self.mag_list = []
		length = len(self.mag_list)
		filtered_magNoG = 0.0


		if length < self.window_size:
			self.mag_list.append(data)
			length += 1
			for i in range(0,length):
				filtered_magNoG = filtered_magNoG + self.mag_list[i]
				filtered_magNoG = filtered_magNoG/length


		elif length == self.window_size:
			for i in range(0, length-1):
				self.mag_list[i] = self.mag_list[i+1]
				filtered_magNoG = filtered_magNoG + self.mag_list[i]
				self.mag_list[length-1] = data
				filtered_magNoG = filtered_magNoG + data
				filtered_magNoG = filtered_magNoG/length
		self.last_time = current_time


		return filtered_magNoG


# -*- mode: python;-*-