L1 Soft Thresholding

Problem

Apply the L1 soft-thresholding operator element-wise: sign(v) * max(|v| - lam, 0).

Return the transformed list; empty input returns [].

Hint

Shrink values toward zero by lam and clamp anything inside [-lam, lam] to zero.

case 1

in: [[3,-2,0.5],1]

expected: [2,-1,0]

case 2

in: [[1],2]

expected: [0]

case 3

in: [[-5,5],0]

expected: [-5,5]

case 4

in: [[],1]

expected: []

Starter codePython

def soft_threshold(values, lam):
    # Your code here
    pass

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