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BUG: df.astype changes order of dataframe #42457

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BUG: df.astype changes order of dataframe #42457

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2 changes: 1 addition & 1 deletion doc/source/whatsnew/v1.3.1.rst
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Expand Up @@ -25,7 +25,7 @@ Fixed regressions

Bug fixes
~~~~~~~~~
-
-Bug in :meth:`pandas.DataFrame.astype` (:issue:`42396`)
-

.. ---------------------------------------------------------------------------
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3 changes: 3 additions & 0 deletions pandas/core/dtypes/cast.py
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Expand Up @@ -1099,6 +1099,9 @@ def astype_nansafe(
flat = arr.ravel("K")
result = astype_nansafe(flat, dtype, copy=copy, skipna=skipna)
order: Literal["C", "F"] = "F" if flags.f_contiguous else "C"
order: Literal["C", "F"] = (
"F" if (not flags.f_contiguous and not flags.c_contiguous) else order
)
# error: Item "ExtensionArray" of "Union[ExtensionArray, ndarray]" has no
# attribute "reshape"
return result.reshape(arr.shape, order=order) # type: ignore[union-attr]
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13 changes: 13 additions & 0 deletions pandas/tests/dtypes/test_dtypes.py
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Expand Up @@ -1095,3 +1095,16 @@ def test_period_dtype_compare_to_string():
dtype = PeriodDtype(freq="M")
assert (dtype == "period[M]") is True
assert (dtype != "period[M]") is False


@pytest.mark.parametrize(
"dtype", ["int_", "int8", "int16", "int32", "uint16", "uint32", "uint64"]
)
def test_dtype_frame_order_astype(dtype):

# GH 42396
npa = np.random.RandomState(0).randint(100, size=(20, 8))
df = pd.DataFrame(npa, columns=[f"c{i}" for i in range(8)])
expected = df.iloc[:6, :3]
result = df.iloc[:6, :3].astype(dtype)
tm.assert_almost_equal(expected, result, check_dtype=False)