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ENH: pandas.api.interchange.from_dataframe now uses the Arrow PyCapsule Interface if available, only falling back to the Dataframe Interchange Protocol if that fails #60739

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Jan 21, 2025
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v3.0.0.rst
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ Other enhancements
^^^^^^^^^^^^^^^^^^
- :class:`pandas.api.typing.FrozenList` is available for typing the outputs of :attr:`MultiIndex.names`, :attr:`MultiIndex.codes` and :attr:`MultiIndex.levels` (:issue:`58237`)
- :class:`pandas.api.typing.SASReader` is available for typing the output of :func:`read_sas` (:issue:`55689`)
- :meth:`pandas.api.interchange.from_dataframe` now uses the [Arrow PyCapsule Interface](https://arrow.apache.org/docs/format/CDataInterface/PyCapsuleInterface.html) if available, only falling back to the Dataframe Interchange Protocol if that fails (:issue:`60739`)
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You'll probably need to use the rst version of making Arrow PyCapsule Interface hyperlink

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thanks, been too long since i made a PR 🤦 😳

- :class:`pandas.api.typing.NoDefault` is available for typing ``no_default``
- :func:`DataFrame.to_excel` now raises an ``UserWarning`` when the character count in a cell exceeds Excel's limitation of 32767 characters (:issue:`56954`)
- :func:`pandas.merge` now validates the ``how`` parameter input (merge type) (:issue:`59435`)
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13 changes: 12 additions & 1 deletion pandas/core/interchange/from_dataframe.py
Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,9 @@ def from_dataframe(df, allow_copy: bool = True) -> pd.DataFrame:
.. note::

For new development, we highly recommend using the Arrow C Data Interface
alongside the Arrow PyCapsule Interface instead of the interchange protocol
alongside the Arrow PyCapsule Interface instead of the interchange protocol.
From pandas 3.0 onwards, `from_dataframe` uses the PyCapsule Interface,
only falling back to the interchange protocol if that fails.

.. warning::

Expand Down Expand Up @@ -90,6 +92,15 @@ def from_dataframe(df, allow_copy: bool = True) -> pd.DataFrame:
if isinstance(df, pd.DataFrame):
return df

if hasattr(df, "__arrow_c_stream__"):
try:
pa = import_optional_dependency("pyarrow", min_version="14.0.0")
except ImportError:
# fallback to _from_dataframe
pass
else:
return pa.table(df).to_pandas(zero_copy_only=not allow_copy)

if not hasattr(df, "__dataframe__"):
raise ValueError("`df` does not support __dataframe__")

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16 changes: 12 additions & 4 deletions pandas/tests/interchange/test_impl.py
Original file line number Diff line number Diff line change
Expand Up @@ -278,7 +278,7 @@ def test_empty_pyarrow(data):
expected = pd.DataFrame(data)
arrow_df = pa_from_dataframe(expected)
result = from_dataframe(arrow_df)
tm.assert_frame_equal(result, expected)
tm.assert_frame_equal(result, expected, check_column_type=False)
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The difference is

(Pdb) p result.columns
Index([], dtype='object')
(Pdb) p expected.columns
RangeIndex(start=0, stop=0, step=1)

Given that this only affects dataframes with zero columns, are we OK with this difference? I am

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Ideally RangeIndex would be better, but OK to punt



def test_multi_chunk_pyarrow() -> None:
Expand All @@ -287,9 +287,8 @@ def test_multi_chunk_pyarrow() -> None:
names = ["n_legs"]
table = pa.table([n_legs], names=names)
with pytest.raises(
RuntimeError,
match="To join chunks a copy is required which is "
"forbidden by allow_copy=False",
pa.ArrowInvalid,
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I think we have generally been trying to catch the pyarrow error internally and raise something more generic from pandas but @mroeschke would know best

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Yes ideally this would be the case, but we're definitely not consistent about it

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sure, i'm catching to re-raise RunTimeError (which is what currently gets raised)

match="Cannot do zero copy conversion into multi-column DataFrame block",
):
pd.api.interchange.from_dataframe(table, allow_copy=False)

Expand Down Expand Up @@ -641,3 +640,12 @@ def test_buffer_dtype_categorical(
col = dfi.get_column_by_name("data")
assert col.dtype == expected_dtype
assert col.get_buffers()["data"][1] == expected_buffer_dtype


def test_from_dataframe_list_dtype():
pa = pytest.importorskip("pyarrow", "14.0.0")
data = {"a": [[1, 2], [4, 5, 6]]}
tbl = pa.table(data)
result = from_dataframe(tbl)
expected = pd.DataFrame(data)
tm.assert_frame_equal(result, expected)
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