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Description
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I have checked that this issue has not already been reported.
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I have confirmed this bug exists on the latest version of pandas.
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(optional) I have confirmed this bug exists on the master branch of pandas.
Code Sample, a copy-pastable example
import pandas as pd
a = pd.DataFrame({"A": pd.array(['a', 'b'], dtype=pd.StringDtype("pyarrow"))})
a.to_parquet("test.parquet")
b = pd.read_parquet("test.parquet")
pd.testing.assert_frame_equal(a, b)
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
/tmp/ipykernel_493/3001616580.py in <module>
3 a.to_parquet("test.parquet")
4 b = pd.read_parquet("test.parquet")
----> 5 pd.testing.assert_frame_equal(a, b)
[... skipping hidden 3 frame]
/srv/conda/envs/notebook/lib/python3.8/site-packages/pandas/_testing/asserters.py in raise_assert_detail(obj, message, left, right, diff, index_values)
663 msg += f"\n[diff]: {diff}"
664
--> 665 raise AssertionError(msg)
666
667
AssertionError: Attributes of DataFrame.iloc[:, 0] (column name="A") are different
Attribute "dtype" are different
[left]: string[pyarrow]
[right]: string[python]Problem description
read_parquet currently loads all string dtype as string[python]. We'd ideally match what was written.
Expected Output
A DataFrame with string[pyarrow] rather than string[python]
Output of pd.show_versions()
INSTALLED VERSIONS
------------------
commit : f00ed8f47020034e752baf0250483053340971b0
python : 3.8.10.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.0-1040-azure
Version : #42~18.04.1-Ubuntu SMP Mon Feb 8 19:05:32 UTC 2021
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : C.UTF-8
LANG : C.UTF-8
LOCALE : en_US.UTF-8
pandas : 1.3.0
numpy : 1.21.0
pytz : 2021.1
dateutil : 2.7.5
pip : 20.3.4
setuptools : 49.6.0.post20210108
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : 1.10.2
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : 2.9.1 (dt dec pq3 ext lo64)
jinja2 : 3.0.1
IPython : 7.25.0
pandas_datareader: None
bs4 : 4.9.3
bottleneck : 1.3.2
fsspec : 2021.06.1
fastparquet : None
gcsfs : 2021.06.1
matplotlib : 3.4.2
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : 4.0.0
pyxlsb : None
s3fs : 2021.06.1
scipy : 1.7.0
sqlalchemy : 1.4.20
tables : None
tabulate : 0.8.9
xarray : 0.18.2
xlrd : None
xlwt : None
numba : 0.53.1
```
</details>