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Different filters for sensor data

Low pass filter for a list input

I.e. (acc_x, acc_y, acc_z)

ALPHA = 0.1

def lowPass( input, output ):
    for i in range(0,len(input)):
        output[i] = (input[i] * ALPHA) + (ouptut[i] * (1.0 - ALPHA))
    return output

High Pass

ALPHA = 0.1

def highPass(  input, gravity ):
    output = []
    for i in range(0,len(input)):
        gravity[i] = (gravity[i]* ALPHA ) + (input[i] *(1-ALPHA))
        output[i] = input[i] - gravity[i]
    return output

Exponential Weighted Moving Average

ALPHA = 0.1
def average(raw_input, filtered_output):
    for i in range(0, len(raw_input)):
        filtered_output[i] = ALPHA*raw_input[i] + (1-ALPHA)*filtered_output[i-1]
    return filtered_output