Additive Seasonal Component

Problem

Estimate an additive seasonal component by averaging deviations from the overall mean per season position. For each position j = 0, ..., period-1 compute the mean of series[j::period] minus the overall mean, then center the component so its entries sum to zero.

Return an empty list if period is not positive or exceeds the series length.

Hint

After centering, the seasonal deviations add up to exactly zero.

Test cases

case 1

in: [[2,4,6,2,4,6],3]

expected: [-2,0,2]

case 2

in: [[1,3,5,2,4,6],3]

expected: [-2,0,2]

case 3

in: [[10,20,30,40],2]

expected: [-5,5]

case 4

in: [[1,2,3],5]

expected: []

Starter codePython

def additive_seasonal_component(series, period):
    # Your code here
    pass

4 test cases · run your code against them in the editor