L2 Regularization Penalty

~10 mincode completion

Implement l2_penalty(weights, lambda_reg) that returns the L2 penalty term .

Examples

Standard case

Input
l2_penalty([1, 2, 3], 0.1)
Output
1.4

Zero weights: penalty = 0

Input
l2_penalty([0, 0, 0], 1)
Output
0

Sign does not matter: squares remove it

Input
l2_penalty([-1, 1, -1, 1], 0.5)
Output
2

Hints

Hint 1

Sum with , and check which axis you are summing over.

Hint 2

Do not forget to lambda scaling. That step is easy to skip.

Requirements

  • weights: Weight vector (any shape)

  • lambda_reg: Regularization strength (lambda)

  • Return Scalar: lambda * sum(weights^2)

Constraints

  • Allowed library: NumPy only

  • Time limit: 200 ms, Memory: 64 MB

Where this shows up

~10 min

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Python
import numpy as np

def l2_penalty(weights: np.ndarray, lambda_reg: float) -> float:
    """
    Compute the L2 regularization penalty.

    Args:
        weights:    Weight vector (any shape)
        lambda_reg: Regularization strength (lambda)

    Returns:
        Scalar: lambda * sum(weights^2)
    """
    # YOUR CODE HERE
    pass
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