Tukey Bisquare Weight

Problem

Compute the Tukey bisquare robust weight.

Return 0.0 when abs(residual) >= c or c is not positive; otherwise return (1 - (residual / c) ** 2) ** 2. The weight decreases smoothly to 0 at the cutoff c.

Hint

The weight reaches zero exactly at the cutoff.

Test cases

case 1

in: [0.5,4]

expected: 0.968994140625

case 2

in: [0,4]

expected: 1

case 3

in: [4,4]

expected: 0

case 4

in: [-2,4]

expected: 0.5625

Starter codePython

def tukey_bisquare_weight(residual, c):
    # Your code here
    pass

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