Z-score Standardization

~10 mincode completion

Implement z_score_standardize(X). Assume the standard deviation is nonzero.

Examples

Symmetric array: mean=0, std=2

Input
z_score_standardize([-3, -1, 0, 1, 3])
Output
[-1.5, -0.5, 0, 0.5, 1.5]

3-element array: known z-scores

Input
z_score_standardize([10, 20, 30])
Output
[-1.22474, 0, 1.22474]

Hints

Hint 1

Work directly with the arguments X and return the result rather than printing it.

Hint 2

Watch for this: divided by variance not std.

Requirements

  • X: NumPy array. Guaranteed std(X) != 0.

  • Return Array of same shape with mean ≈ 0 and std ≈ 1.

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 z_score_standardize(X: np.ndarray) -> np.ndarray:
    """
    Standardize X to zero mean and unit variance.

    Args:
        X: NumPy array. Guaranteed std(X) != 0.

    Returns:
        Array of same shape with mean ≈ 0 and std ≈ 1.
    """
    # YOUR CODE HERE
    pass
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