21. R-squared
r2_score()Asked in screens shaped like: Databricks, Google
Return 1 - SS_res / SS_tot for y_true vs y_pred, rounded to 4 decimals. SS_tot uses the mean of y_true.
Examples
Example 1
Input: { "y_true": [1, 2, 3], "y_pred": [1, 2, 5] } Output: -1
Constraints
- Arrays are the same length and y_true is not constant
Implement r2_score(). Types below are the NumPy contract; Python and PyTorch use lists or tensors with the same names.
| Name | Type | I/O |
|---|---|---|
| y_true | array | Input |
| y_pred | array | Input |
| value | float | Output |
Same tests, three APIs. Pick a language with the chips above the editor.
NumPy
Vectorized arrays. Default for analyst, scientist, and DE screens.
Revealed one at a time. The reference implementation stays in the Solution tab.
Hint 1
Keep the function signature. Fill the body — do not rename parameters.
Hint 2
Match the rounding in the examples. Tests compare with a small numeric tolerance.
Hint 3
Switch NumPy / Python / PyTorch with the chips above the editor. Each language has its own tests.
Run your code to see stdout.
Submit to run the checks.
All tests passed on this language.
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