A few cudf fixups

[jcrist]

Some recent cudf changes (due to fixing NVIDIA/cudf#22136) have caused some test failures.

• Fixes failing test
• Removes no longer needed workaround

[coderabbitai]

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 4b66e2c and e915b36.

📒 Files selected for processing (2)

• python/cuml/cuml/internals/validation.py
• python/cuml/tests/test_validation.py

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📝 Walkthrough

Summary by CodeRabbit

• Bug Fixes
  • Streamlined dtype conversion in array validation for improved performance
  • Fixed validation behavior when handling float16 data types

Walkthrough

The PR refactors dtype coercion in cuML's array validation. check_array's dense CUDA/cuDF conversion now passes dtype directly to cudf.to_cupy(dtype=dtype) instead of performing manual pre-casting with astype(), removing workaround comments. The corresponding test adjusts how float16 inputs are normalized during NumPy conversion for comparison.

Changes

cuDF dtype coercion fixes

Layer / File(s)	Summary
Dense conversion dtype coercion python/cuml/cuml/internals/validation.py, python/cuml/tests/test_validation.py	check_array now relies on cudf.to_cupy(dtype=dtype) for dtype coercion, removing the manual astype() workaround step. Tests adjust float16 input handling during NumPy conversion to ensure consistent comparison.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• rapidsai/cuml#8038: Both PRs modify the check_array dense CUDA/cuDF conversion path in validation.py to change dtype coercion handling via cudf.to_* calls, directly connected at the code level.

Suggested labels

Cython / Python

Suggested reviewers

• divyegala
• csadorf

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Title check	❓ Inconclusive	The title 'A few cudf fixups' is vague and generic, using non-descriptive terms that don't clearly convey the specific changes being made.	Consider a more descriptive title like 'Fix dtype handling in check_array cudf conversion and update test expectations'.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description check	✅ Passed	The description is related to the changeset, referencing recent cudf changes and mentioning test fixes and workaround removal.
Linked Issues check	✅ Passed	The PR addresses issue #22136 by removing the workaround for to_cupy(dtype=...) that was failing with cudf changes, and updates test expectations accordingly.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing cudf compatibility issues; the modifications to validation.py and test_validation.py align with the stated objective of addressing cudf #22136.

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[jcrist]

/merge

[csadorf]

/merge