Rolling Skewness

Problem

Compute the rolling population skewness with window size k: mean((x - window_mean)^3) / std^3, where std is the population standard deviation.

Return an empty list if k is not positive or exceeds the series; windows with zero variance produce 0.0.

Hint

Positive skewness means a long right tail.

case 1

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

expected: [0,0,0]

case 2

in: [[1,2,10],3]

expected: [0.6745554845457659]

case 3

in: [[1,1,1,2,10],3]

expected: [0,0.707106781186548,0.6745554845457659]

case 4

in: [[5,5,5],1]

expected: [0,0,0]

Starter codePython

def rolling_skewness(series, k):
    # Your code here
    pass

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