BUG: pandas int extension dtypes has no attribute byteorder

[mvashishtha]

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Reproducible Example

import pandas as pd

df = pd.DataFrame({'a': [1]}, dtype=pd.Int8Dtype())
pd.api.interchange.from_dataframe(df.__dataframe__())

Issue Description

I'm trying to use the dataframe interchange protocol with pandas dataframes holding int extension dtypes, but I can't convert to interchange and back because the extension dtypes don't have a byteorder attribute.

Details

---

AttributeError Traceback (most recent call last)
Cell In[7], line 4
1 import pandas as pd
3 df = pd.DataFrame({'a': [1]}, dtype=pd.Int8Dtype())
----> 4 pd.api.interchange.from_dataframe(df.dataframe())

File ~/anaconda3/envs/ponder-dev/lib/python3.8/site-packages/pandas/core/interchange/from_dataframe.py:54, in from_dataframe(df, allow_copy)
51 if not hasattr(df, "dataframe"):
52 raise ValueError("df does not support dataframe")
---> 54 return _from_dataframe(df.dataframe(allow_copy=allow_copy))

File ~/anaconda3/envs/ponder-dev/lib/python3.8/site-packages/pandas/core/interchange/from_dataframe.py:75, in _from_dataframe(df, allow_copy)
73 pandas_dfs = []
74 for chunk in df.get_chunks():
---> 75 pandas_df = protocol_df_chunk_to_pandas(chunk)
76 pandas_dfs.append(pandas_df)
78 if not allow_copy and len(pandas_dfs) > 1:

File ~/anaconda3/envs/ponder-dev/lib/python3.8/site-packages/pandas/core/interchange/from_dataframe.py:116, in protocol_df_chunk_to_pandas(df)
114 raise ValueError(f"Column {name} is not unique")
115 col = df.get_column_by_name(name)
--> 116 dtype = col.dtype[0]
117 if dtype in (
118 DtypeKind.INT,
119 DtypeKind.UINT,
120 DtypeKind.FLOAT,
121 DtypeKind.BOOL,
122 ):
123 columns[name], buf = primitive_column_to_ndarray(col)

File ~/anaconda3/envs/ponder-dev/lib/python3.8/site-packages/pandas/_libs/properties.pyx:36, in pandas._libs.properties.CachedProperty.get()

File ~/anaconda3/envs/ponder-dev/lib/python3.8/site-packages/pandas/core/interchange/column.py:126, in PandasColumn.dtype(self)
124 raise NotImplementedError("Non-string object dtypes are not supported yet")
125 else:
--> 126 return self._dtype_from_pandasdtype(dtype)

File ~/anaconda3/envs/ponder-dev/lib/python3.8/site-packages/pandas/core/interchange/column.py:141, in PandasColumn._dtype_from_pandasdtype(self, dtype)
137 if kind is None:
138 # Not a NumPy dtype. Check if it's a categorical maybe
139 raise ValueError(f"Data type {dtype} not supported by interchange protocol")
--> 141 return kind, dtype.itemsize * 8, dtype_to_arrow_c_fmt(dtype), dtype.byteorder

AttributeError: 'Int8Dtype' object has no attribute 'byteorder'

Expected Behavior

pd.api.interchange.from_dataframe(df.__dataframe__()) should not raise an error and should give back the original dataframe.

Installed Versions

INSTALLED VERSIONS

commit : 0f43794
python : 3.8.16.final.0
python-bits : 64
OS : Darwin
OS-release : 22.6.0
Version : Darwin Kernel Version 22.6.0: Wed Jul 5 22:21:56 PDT 2023; root:xnu-8796.141.3~6/RELEASE_X86_64
machine : x86_64
processor : i386
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 2.0.3
numpy : 1.24.3
pytz : 2023.3
dateutil : 2.8.2
setuptools : 67.8.0
pip : 23.2.1
Cython : None
pytest : 7.3.1
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : 3.1.2
lxml.etree : 4.9.3
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.12.0
pandas_datareader: None
bs4 : 4.12.2
bottleneck : None
brotli : None
fastparquet : None
fsspec : 2023.6.0
gcsfs : None
matplotlib : 3.7.1
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : 10.0.1
pyreadstat : None
pyxlsb : None
s3fs : 0.4.2
scipy : 1.10.1
snappy : None
sqlalchemy : 2.0.19
tables : None
tabulate : 0.9.0
xarray : None
xlrd : None
zstandard : 0.21.0
tzdata : 2023.3
qtpy : None
pyqt5 : None

[rhshadrach]

cc @MarcoGorelli

[MarcoGorelli]

thanks for the report and tag, will take a look

[timvink]

I suspect this affects scikit-learn also, see scikit-learn/scikit-learn#28317

[MarcoGorelli]

thanks - this bumps up the urgency then, will address it