R-squared Score

~15 mincode completion

Implement r_squared(y_true, y_pred).

Examples

Perfect predictions: R2 = 1.0

Input
r_squared([1, 2, 3, 4, 5], [1, 2, 3, 4, 5])
Output
1

Predicting the mean: R2 = 0.0

Input
r_squared([2, 4, 6, 8, 10], [6, 6, 6, 6, 6])
Output
0

Good but not perfect predictions

Input
r_squared([1, 2, 3], [1.5, 2, 2.5])
Output
0.75

Hints

Hint 1

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

Hint 2

Watch for this: computed ss tot as variance not sum.

Requirements

  • y_true: Ground truth values, shape (m,)

  • y_pred: Predicted values, shape (m,)

  • Return R² score (float). Can be negative.

Constraints

  • Allowed library: NumPy only

  • Time limit: 200 ms, Memory: 64 MB

Where this shows up

~15 min

8 employers weight this skill

2 health and bio companies, 2 quant funds, 2 enterprise vendors, 1 AI product company, 1 frontier lab. Top match scores 87.

Python
import numpy as np

def r_squared(y_true: np.ndarray, y_pred: np.ndarray) -> float:
    """
    Compute the R-squared score.

    Args:
        y_true: Ground truth values, shape (m,)
        y_pred: Predicted values, shape (m,)

    Returns:
        R² score (float). Can be negative.
    """
    # YOUR CODE HERE
    pass
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