Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [547]: df = pd.DataFrame( .... supported types include Interval and actual Python object types. These will raise a helpful error message on an attempt at serialization. Period type is supported with pyarrow >= 0.16.0. • The pyarrow engine analysis toolkit, Release 1.3.3 (continued from previous page) label X [0, 2] Y [1, 3] This error message contains the labels that are duplicated, and the numeric positions of all the duplicates (including

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [547]: df = pd.DataFrame( .... supported types include Interval and actual Python object types. These will raise a helpful error message on an attempt at serialization. Period type is supported with pyarrow >= 0.16.0. • The pyarrow engine analysis toolkit, Release 1.3.4 (continued from previous page) label X [0, 2] Y [1, 3] This error message contains the labels that are duplicated, and the numeric positions of all the duplicates (including

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [590]: df = pd.DataFrame( .... supported types include Interval and actual Python object types. These will raise a helpful error message on an attempt at serialization. Period type is supported with pyarrow >= 0.16.0. • The pyarrow engine toolkit, Release 1.4.4 (continued from previous page) 712 duplicates = self._format_duplicate_message() 713 msg += f"\n{duplicates}" --> 715 raise DuplicateLabelError(msg) DuplicateLabelError: Index

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [551]: df = pd.DataFrame( .... supported types include Interval and actual Python object types. These will raise a helpful error message on an attempt at serialization. Period type is supported with pyarrow >= 0.16.0. • The pyarrow engine toolkit, Release 1.4.2 (continued from previous page) 712 duplicates = self._format_duplicate_message() 713 msg += f"\n{duplicates}" --> 715 raise DuplicateLabelError(msg) DuplicateLabelError: Index

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [547]: df = pd.DataFrame( .... @final DuplicateLabelError: Index has duplicates. positions label X [0, 2] Y [1, 3] This error message contains the labels that are duplicated, and the numeric positions of all the duplicates (including default ‘DataFrame’] Specify object name being compared, internally used to show appropriate assertion message. See also: assert_series_equal Equivalent method for asserting Series equality. DataFrame.equals

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [499]: df = pd.DataFrame({'a': list('abc') found (oth- erwise it would raise a KeyError). This behavior is deprecated and will show a warning message pointing to this section. The recommended alternative is to use .reindex(). For example. In [98]: default ‘DataFrame’] Specify object name being compared, internally used to show appropriate assertion message. See also: assert_series_equal Equivalent method for asserting Series equality. DataFrame.equals

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [499]: df = pd.DataFrame({'a': list('abc') found (oth- erwise it would raise a KeyError). This behavior is deprecated and will show a warning message pointing to this section. The recommended alternative is to use .reindex(). For example. In [98]: default ‘DataFrame’] Specify object name being compared, internally used to show appropriate assertion message. See also: assert_series_equal Equivalent method for asserting Series equality. DataFrame.equals

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [589]: df = pd.DataFrame( .... supported types include Interval and actual Python object types. These will raise a helpful error message on an attempt at serialization. Period type is supported with pyarrow >= 0.16.0. • The pyarrow engine ndexes/base.py:752, in Index._maybe_check_unique(self) 749 duplicates = self._format_duplicate_message() 750 msg += f"\n{duplicates}" --> 752 raise DuplicateLabelError(msg) DuplicateLabelError: Index

Actual Python objects in object dtype columns are not supported. These will raise a helpful error message on an attempt at serialization. See the Full Documentation. In [498]: df = pd.DataFrame( .... @final DuplicateLabelError: Index has duplicates. positions label X [0, 2] Y [1, 3] This error message contains the labels that are duplicated, and the numeric positions of all the duplicates (including default ‘DataFrame’] Specify object name being compared, internally used to show appropriate assertion message. See also: assert_series_equal Equivalent method for asserting Series equality. DataFrame.equals

Bug fixes 1.9.1 Categorical • Added test to assert the fillna() raises the correct ValueError message when the value isn’t a value from categories (GH13628) • Bug in Categorical.astype() where NaN values read_parquet() will preserve Categorical dtypes for string types (GH27955) • Changed the error message in Categorical.remove_categories() to always show the invalid re- movals as a set (GH28669) • Using where attempting to drop non-existent values from a DatetimeIndex would yield a confusing error message (GH30399) • Bug in DataFrame.append() would remove the timezone-awareness of new data (GH30238)