list = [100, 90, 81, 70, 72, 75, 85, 57, 90, 97, 105, 107, 105, 95, 120, 82, 72, 61, 49, 25, 53, 55]
# list[7], list[14] and list[19] are the outliers in this scenario.
# outliers should not exist in first 4 numbers.

# 실시간을 가정한 것이라 n 이후의 값을 내다 볼 수 없다는 전제 하에 작동.


# error tolerance level
etl = 0.2

minimum = 1 - etl
maximum = 1 + etl

# predict list[n]
n = 4

for i in range(0, len(list) - 4):
        p1 = list[n-1]
        p2 = list[n-2]
        p3 = list[n-3]
        p4 = list[n-4]
        delta = ((p1 - p2) + (p2 - p3) + (p3 - p4)) / 3
        prediction = list[n-1] + delta

        if prediction*minimum <= list[n] <= prediction*maximum:
            pass
        else:
            list[n] = int(prediction)

        print(list)

        n += 1
        i += 1