Rolling Median

Problem

Compute the rolling median of a series with window size k, which is far more robust to spikes than a rolling mean. Sort each window; for odd k take the middle value, for even k average the two middle values.

Return an empty list if k is not positive or k is larger than the series.

Hint

Two middle indices for even windows: k//2 - 1 and k//2.

Test cases

case 1

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

expected: [2,3,4]

case 2

in: [[4,2,7,1],2]

expected: [3,4.5,4]

case 3

in: [[5],1]

expected: [5]

case 4

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

expected: [2]

Starter codePython

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

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