How to use ncols_gt method in pandera

Best Python code snippet using pandera_python

test_io.py

Source:test_io.py

...488    Tests that writing DataFrameSchema with a registered dataframe check works.489    """490    ncols_gt_called = False491    @pa_ext.register_check_method(statistics=["column_count"])492    def ncols_gt(pandas_obj: pd.DataFrame, column_count: int) -> bool:493        """test registered dataframe check"""494        # pylint: disable=unused-variable495        nonlocal ncols_gt_called496        ncols_gt_called = True497        assert isinstance(column_count, int), "column_count must be integral"498        assert isinstance(499            pandas_obj, pd.DataFrame500        ), "ncols_gt should only be applied to DataFrame"501        return len(pandas_obj.columns) > column_count502    assert (503        len(pandera.Check.REGISTERED_CUSTOM_CHECKS) == 1504    ), "custom check is registered"505    schema = pandera.DataFrameSchema(506        {507            "a": pandera.Column(508                pandera.Int,509            ),510        },511        checks=[pandera.Check.ncols_gt(column_count=5)],512    )513    serialized = pandera.io.to_yaml(schema)514    loaded = pandera.io.from_yaml(serialized)515    assert len(loaded.checks) == 1, "global check was stripped"516    with pytest.raises(pandera.errors.SchemaError):517        schema.validate(pd.DataFrame(data={"a": [1]}))518    assert ncols_gt_called, "did not call ncols_gt"519def test_to_yaml_custom_dataframe_check():520    """Tests that writing DataFrameSchema with an unregistered check raises."""521    schema = pandera.DataFrameSchema(522        {523            "a": pandera.Column(524                pandera.Int,525            ),...

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