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BUG: `sort_values` is destructive after `join` #6601

Closed zmbc closed 11 months ago

zmbc commented 11 months ago

Modin version checks

Reproducible Example

import modin.pandas as pd

abbreviations = pd.Series(['Major League Baseball', 'National Basketball Association'], index=['MLB', 'NBA'])

teams = pd.DataFrame({'name': ['Mariners', 'Lakers'] * 500, 'league_abbreviation': ['MLB', 'NBA'] * 500})

# This all works correctly (or seems to -- the sort_values breaks things below the surface)
joined = teams.set_index('league_abbreviation').join(abbreviations.rename('league_name'))
print(joined)
sort_values_result = joined.sort_values('league_name')
print(sort_values_result)
# This breaks!
print(joined)

Issue Description

Calling sort_values has a destructive effect on the value of the dataframe. Some minimal debugging shows it has somehow lost the sorted column:

> ~/src/modin/modin/core/dataframe/pandas/dataframe/dataframe.py(4028)to_pandas()
-> ErrorMessage.catch_bugs_and_request_email(
(Pdb) ll
4006        @lazy_metadata_decorator(apply_axis="both")
4007        def to_pandas(self):
4008            """
4009            Convert this Modin DataFrame to a pandas DataFrame.
4010 
4011            Returns
4012            -------
4013            pandas.DataFrame
4014            """
4015            df = self._partition_mgr_cls.to_pandas(self._partitions)
4016            if df.empty:
4017                df = pandas.DataFrame(columns=self.columns, index=self.index)
4018                if len(df.columns) and self.has_materialized_dtypes:
4019                    df = df.astype(self.dtypes)
4020            else:
4021                for axis, has_external_index in enumerate(
4022                    ["has_materialized_index", "has_materialized_columns"]
4023                ):
4024                    # no need to check external and internal axes since in that case
4025                    # external axes will be computed from internal partitions
4026                    if getattr(self, has_external_index):
4027                        external_index = self.columns if axis else self.index
4028 ->                     ErrorMessage.catch_bugs_and_request_email(
4029                            not df.axes[axis].equals(external_index),
4030                            f"Internal and external indices on axis {axis} do not match.",
4031                        )
4032                        # have to do this in order to assign some potentially missing metadata,
4033                        # the ones that were set to the external index but were never propagated
4034                        # into the internal ones
4035                        df = df.set_axis(axis=axis, labels=external_index, copy=False)
4036 
4037            return df
(Pdb) df.axes[axis]
Index(['name'], dtype='object')
(Pdb) external_index
Index(['name', 'league_name'], dtype='object'

Note that simply changing joined.sort_values to joined.copy().sort_values fixes the problem in the example above.

I am guessing this does not actually have to do with joining, but probably is a result of these columns being in different partitions?

Expected Behavior

The joined dataframe is unaffected by the sort_values call.

Error Logs

```python-traceback Traceback (most recent call last): File "~/mambaforge/envs/modin/lib/python3.10/pdb.py", line 1723, in main pdb._runscript(mainpyfile) File "~/mambaforge/envs/modin/lib/python3.10/pdb.py", line 1583, in _runscript self.run(statement) File "~/mambaforge/envs/modin/lib/python3.10/bdb.py", line 598, in run exec(cmd, globals, locals) File "", line 1, in File "~/src/modin/test_sort_values_join.py", line 18, in print(joined) File "~/mambaforge/envs/modin/lib/python3.10/site-packages/ray/experimental/tqdm_ray.py", line 48, in safe_print _print(*args, **kwargs) File "~/src/modin/modin/logging/logger_decorator.py", line 129, in run_and_log return obj(*args, **kwargs) File "~/src/modin/modin/pandas/base.py", line 3997, in __str__ return repr(self) File "~/src/modin/modin/logging/logger_decorator.py", line 129, in run_and_log return obj(*args, **kwargs) File "~/src/modin/modin/pandas/dataframe.py", line 246, in __repr__ result = repr(self._build_repr_df(num_rows, num_cols)) File "~/src/modin/modin/logging/logger_decorator.py", line 129, in run_and_log return obj(*args, **kwargs) File "~/src/modin/modin/pandas/base.py", line 261, in _build_repr_df return self.iloc[indexer]._query_compiler.to_pandas() File "~/src/modin/modin/logging/logger_decorator.py", line 129, in run_and_log return obj(*args, **kwargs) File "~/src/modin/modin/core/storage_formats/pandas/query_compiler.py", line 282, in to_pandas return self._modin_frame.to_pandas() File "~/src/modin/modin/logging/logger_decorator.py", line 129, in run_and_log return obj(*args, **kwargs) File "~/src/modin/modin/core/dataframe/pandas/dataframe/utils.py", line 501, in run_f_on_minimally_updated_metadata result = f(self, *args, **kwargs) File "~/src/modin/modin/core/dataframe/pandas/dataframe/dataframe.py", line 4028, in to_pandas ErrorMessage.catch_bugs_and_request_email( File "~/src/modin/modin/error_message.py", line 81, in catch_bugs_and_request_email raise Exception( Exception: Internal Error. Please visit https://github.com/modin-project/modin/issues to file an issue with the traceback and the command that caused this error. If you can't file a GitHub issue, please email bug_reports@modin.org. Internal and external indices on axis 1 do not match. ```

Installed Versions

INSTALLED VERSIONS ------------------ commit : ea8088af4cadfb76294e458e5095f262ca85fea9 python : 3.10.12.final.0 python-bits : 64 OS : Linux OS-release : 5.4.0-135-generic Version : #152-Ubuntu SMP Wed Nov 23 20:19:22 UTC 2022 machine : x86_64 processor : x86_64 byteorder : little LC_ALL : None LANG : en_US.UTF-8 LOCALE : en_US.UTF-8 Modin dependencies ------------------ modin : 0.23.0+108.gea8088af ray : 2.6.1 dask : 2023.7.1 distributed : 2023.7.1 hdk : None pandas dependencies ------------------- pandas : 2.1.1 numpy : 1.25.1 pytz : 2023.3 dateutil : 2.8.2 setuptools : 68.0.0 pip : 23.2.1 Cython : None pytest : 7.4.0 hypothesis : None sphinx : 7.1.0 blosc : None feather : 0.4.1 xlsxwriter : None lxml.etree : 4.9.3 html5lib : None pymysql : None psycopg2 : 2.9.6 jinja2 : 3.1.2 IPython : 8.14.0 pandas_datareader : None bs4 : 4.12.2 bottleneck : None dataframe-api-compat: None fastparquet : 2022.12.0 fsspec : 2023.6.0 gcsfs : None matplotlib : 3.7.2 numba : None numexpr : 2.8.4 odfpy : None openpyxl : 3.1.2 pandas_gbq : 0.15.0 pyarrow : 12.0.1 pyreadstat : None pyxlsb : None s3fs : 2023.6.0 scipy : 1.11.1 sqlalchemy : 1.4.45 tables : 3.8.0 tabulate : None xarray : None xlrd : 2.0.1 zstandard : None tzdata : 2023.3 qtpy : 2.3.1 pyqt5 : None
anmyachev commented 11 months ago

Thanks @zmbc! I can reproduce the problem.