[Fix] move calibrate load dataset location

[43758726]

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Motivation

Avoiding finding dataset module when not using lite module.

Modification

Move load_dataset location from outside to the function of get_calib_loaders in lmdeploy/lmdeploy/lite/utils/calib_dataloader.py.

Checklist

1. Pre-commit or other linting tools are used to fix the potential lint issues.
2. The modification is covered by complete unit tests. If not, please add more unit tests to ensure the correctness.
3. If the modification has a dependency on downstream projects of a newer version, this PR should be tested with all supported versions of downstream projects.
4. The documentation has been modified accordingly, like docstring or example tutorials.

[Copilot]

Pull request overview

Moves Hugging Face datasets loading/imports into get_calib_loaders to prevent datasets being imported at module import time when lite calibration isn’t used.

Changes:

• Removed module-level datasets imports and relocated load_dataset calls into get_calib_loaders.
• Updated dataset-specific helper functions (get_wikitext2, get_c4, etc.) to accept a pre-loaded dataset argument instead of calling load_dataset internally.

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[Copilot]

get_calib_loaders unconditionally imports datasets at runtime. If datasets is an optional dependency (as implied by the motivation), consider wrapping this import in a try/except ImportError and raising a clearer error instructing users how to install the lite/extra requirements, rather than propagating a bare ModuleNotFoundError.

Suggested change

	from datasets import VerificationMode, load_dataset
	try:
	from datasets import VerificationMode, load_dataset
	except ImportError as e:
	raise ImportError(
	"The 'datasets' package is required to use calibration data loaders. "
	"Please install lmdeploy with the 'lite' extra (e.g. `pip install lmdeploy[lite]`) "
	"or install the 'datasets' package directly."
	) from e

[Copilot]

The InterruptedError message concatenates two string literals without a separating space: "replace the data_files" + "with local addresses...", which renders as "data_fileswith". Add a trailing/leading space so the error message is readable.

Suggested change

	'with local addresses or use other datasets '
	' with local addresses or use other datasets '

[Copilot]

This change is intended to avoid importing datasets at module import time; there are no unit tests covering this behavior (e.g., that import lmdeploy.lite.utils.calib_dataloader succeeds when datasets is not installed, and that get_calib_loaders still calls load_dataset for each supported name). Please add tests that mock/monkeypatch datasets.load_dataset (and simulate ImportError for datasets) to prevent regressions without requiring network downloads.