check_fit_transform_equivalence

yohou.testing.transformer.check_fit_transform_equivalence(transformer, X, y=None)

Check fit_transform(X) == fit(X).transform(X).

The convenience method fit_transform should produce identical results to separate fit and transform calls.

Parameters

Name	Type	Description	Default
transformer	BaseTransformer	Unfitted transformer	required
X	DataFrame	Training data	required
y	DataFrame	Target data	None

Raises

Type	Description
AssertionError	If methods produce different results

Source Code

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def check_fit_transform_equivalence(transformer, X: pl.DataFrame, y: pl.DataFrame | None = None) -> None:
    """Check fit_transform(X) == fit(X).transform(X).

    The convenience method fit_transform should produce identical
    results to separate fit and transform calls.

    Parameters
    ----------
    transformer : BaseTransformer
        Unfitted transformer
    X : pl.DataFrame
        Training data
    y : pl.DataFrame, optional
        Target data

    Raises
    ------
    AssertionError
        If methods produce different results

    """
    transformer1 = clone(transformer)
    transformer2 = clone(transformer)

    # Separate fit and transform
    X_trans1 = transformer1.fit(X, y).transform(X)

    # Combined fit_transform
    if hasattr(transformer2, "fit_transform"):
        X_trans2 = transformer2.fit_transform(X, y)
    else:
        # Default implementation from TransformerMixin
        X_trans2 = transformer2.fit(X, y).transform(X)

    assert_frame_equal(X_trans1, X_trans2, rel_tol=1e-7, abs_tol=1e-10)