fix: import scikit-learn lazily in openstef-beam r2 metric#981
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fix: import scikit-learn lazily in openstef-beam r2 metric#981Valyrian-Code wants to merge 4 commits into
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scikit-learn is an optional dependency of openstef-beam (not declared in its dependencies), but metrics_deterministic imported r2_score at module top, so importing openstef_beam.metrics failed when scikit-learn was not installed. Move the import inside r2() (its only use site) so the metrics module imports without scikit-learn; only calling r2() needs it. Add regression tests. Signed-off-by: RAJVEER42 <irajveer.bishnoi2310@gmail.com>
egordm
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Jun 25, 2026
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Not sure about this one. R2 is used as default in many openstef components. Making the import lazy would notify users only at runtime that they are missing a dependency.
I don't think making it lazy is the right approach.
It is really tempting to inline R2 though, which would remove openstef-beam's dependency on sklearn.
Per @egordm's review on OpenSTEF#981: instead of lazily importing sklearn's r2_score, compute R2 directly with numpy so openstef-beam no longer depends on scikit-learn at all. Matches scikit-learn's r2_score including sample weights and the constant-y_true convention (1.0 for a perfect fit, else 0.0). Signed-off-by: RAJVEER42 <irajveer.bishnoi2310@gmail.com>
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Good call, thanks! I've inlined the R2 computation in numpy, so openstef-beam no longer depends on scikit-learn at all rather than just deferring the import to runtime. It matches scikit-learn's |
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What
scikit-learnis an optional dependency ofopenstef-beam(it is not declared in the package's dependencies), butmetrics_deterministic.pyimportedr2_scorefromsklearn.metricsat module top. As a result, importingopenstef_beam.metrics(or anything that pulls it in) failed withModuleNotFoundErrorwhen scikit-learn was not installed. Resolves #805.Fix
Move the
from sklearn.metrics import r2_scoreimport inside ther2()function, its only use site. Importing the module no longer requires scikit-learn; only callingr2()does.Tests
test_r2_score_is_imported_lazily: assertsr2_scoreis not bound at module level (locks the lazy import).test_r2_still_computes_with_sklearn_available: confirmsr2()still computes correctly.ty check,ruff check,ruff format --check, the module doctests, and the full beam metrics suite all pass.