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Reproducible Example

import pandas as pd
import pint
import pint_pandas

s = pd.Series([1.2345678, 2.3456789])
s.round(2)

df_pint = pd.DataFrame([1.2345678, 2.3456789], dtype='pint[m]')
df_pint.round(2)


s_pint = pd.Series([1.2345678, 2.3456789], dtype='pint[m]')
s_pint.round(2) # this errors

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Input In [19], in <cell line: 13>()
      9 df_pint.round(2)
     12 s_pint = pd.Series([1.2345678, 2.3456789], dtype='pint[m]')
---> 13 s_pint.round(2)

File ~\anaconda3\envs\pint-pandas-oct22\lib\site-packages\pandas\core\series.py:2602, in Series.round(self, decimals, *args, **kwargs)
   2570 """
   2571 Round each value in a Series to the given number of decimals.
   2572 
   (...)
   2599 dtype: float64
   2600 """
   2601 nv.validate_round(args, kwargs)
-> 2602 result = self._values.round(decimals)
   2603 result = self._constructor(result, index=self.index).__finalize__(
   2604     self, method="round"
   2605 )
   2607 return result

AttributeError: 'PintArray' object has no attribute 'round'

Issue Description

Series.round() expects ExtensionArray.round() to be implemented. ExtensionArray.round() isn't mentioned in any docs, so I'm suprised to see this error. Should EAs implement a round method?

Some previous discussion here, but with a different error message https://github.com/pandas-dev/pandas/issues/26730

Expected Behavior

A note in EA docs to implement round if that's needed.

Installed Versions

INSTALLED VERSIONS ------------------ commit : 91111fd99898d9dcaa6bf6bedb662db4108da6e6 python : 3.10.6.final.0 python-bits : 64 OS : Windows OS-release : 10 Version : 10.0.19044 machine : AMD64 processor : Intel64 Family 6 Model 151 Stepping 2, GenuineIntel byteorder : little LC_ALL : None LANG : None LOCALE : English_United Kingdom.1252 pandas : 1.5.1 numpy : 1.23.3 pytz : 2022.1 dateutil : 2.8.2 setuptools : 63.4.1 pip : 22.2.2 Cython : None pytest : 7.2.0 hypothesis : None sphinx : None blosc : None feather : None xlsxwriter : None lxml.etree : None html5lib : None pymysql : None psycopg2 : None jinja2 : None IPython : 8.4.0 pandas_datareader: None bs4 : None bottleneck : 1.3.5 brotli : None fastparquet : None fsspec : None gcsfs : None matplotlib : 3.5.2 numba : None numexpr : 2.8.3 odfpy : None openpyxl : None pandas_gbq : None pyarrow : None pyreadstat : None pyxlsb : None s3fs : None scipy : None snappy : None sqlalchemy : None tables : None tabulate : None xarray : None xlrd : None xlwt : None zstandard : None tzdata : None

Comment From: codestorm177

Thank you for giving a detailed description. Looking into this now

Comment From: topper-123

ExtensionArray can hold data that don't require a round method, I don't think this is an issue with ExtensionArray itself.

Probably there should be an abstract round method in ExtensionOpsMixin.