Anomaly Z-Score on Residuals

Problem

Score a new value against a list of residuals. Compute the mean and population standard deviation of residuals, then return (value - mean) / std.

Return 0.0 if residuals is empty or has zero variance.

Hint

A z-score beyond 2 flags a potentially unusual observation.

case 1

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

expected: 2.23606797749979

case 2

in: [[0,0,0],1]

expected: 0

case 3

in: [[10,10,10,10],10]

expected: 0

case 4

in: [[2,4,6],8]

expected: 2.449489742783178

Starter codePython

def anomaly_zscore(residuals, value):
    # Your code here
    pass

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