BUG: Fixed bug when creating new column with missing values when setting a single string value #56321
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MarcoGorelli force-pushed the pdep6-regression branch from 00bed88 to b3774b1 Compare 
phofl reviewed Dec 6, 2023
doc/source/whatsnew/v2.1.4.rst Outdated
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| Fixed regressions | ||
| ~~~~~~~~~~~~~~~~~ | ||
| - Fixed bug when creating new column with missing values when setting a single string value (:issue:`56204`) |
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Can you put this into the bug column?
phofl reviewed Dec 6, 2023
mroeschke added Strings 
jbrockmendel reviewed Dec 6, 2023
| def test_adding_new_conditional_column_with_string() -> None: | ||
| # https://github.com/pandas-dev/pandas/issues/56204 | ||
| df = DataFrame({"a": [1, 2], "b": [3, 4]}) | ||
| df.loc[lambda x: x.a == 1, "c"] = "1" |
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is it important that this be a lambda?
jbrockmendel reviewed Dec 6, 2023
| tm.assert_frame_equal(df, expected) | ||
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| def test_adding_new_conditional_column_with_infer_string() -> None: |
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maybe make this one test and parametrize? in 3.0 we'll only want to end up with one test here right?
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| thanks for your reviews! have updated |
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| Just tracked down an old branch where past-me was trying to get rid of infer_fill_value. The only recoverable bit of that branch looks like it would go just before L1880 in indexing.py would that solve the issue here robustly? i like past-me's idea of using sanitize_array rather than yet-another constructor-esque function |
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| That would also avoid the warning when expanding column-wise: main: In [1]: df = pd.DataFrame({'a': [.1, .2], 'b': [.3, .4]}) In [2]: df.loc[1, 'c'] = True <ipython-input-2-d3d953ae007a>:1: FutureWarning: Setting an item of incompatible dtype is deprecated and will raise in a future error of pandas. Value 'True' has dtype incompatible with float64, please explicitly cast to a compatible dtype first. df.loc[1, 'c'] = True In [3]: df Out[3]: a b c 0 0.1 0.3 NaN 1 0.2 0.4 True In [4]: df.dtypes Out[4]: a float64 b float64 c object dtype: objecthere: In [1]: df = pd.DataFrame({'a': [.1, .2], 'b': [.3, .4]}) In [2]: df.loc[1, 'c'] = True In [3]: df Out[3]: a b c 0 0.1 0.3 NaN 1 0.2 0.4 True In [4]: df.dtypes Out[4]: a float64 b float64 c object dtype: object |
mroeschke reviewed Dec 20, 2023
doc/source/whatsnew/v2.1.4.rst Outdated
| - Fixed bug in :meth:`Series.reset_index` not preserving object dtype when ``infer_string`` is set (:issue:`56160`) | ||
| - Fixed bug in :meth:`Series.str.split` and :meth:`Series.str.rsplit` when ``pat=None`` for :class:`ArrowDtype` with ``pyarrow.string`` (:issue:`56271`) | ||
| - Fixed bug in :meth:`Series.str.translate` losing object dtype when string option is set (:issue:`56152`) | ||
| - Fixed bug when creating new column with missing values when setting a single string value (:issue:`56204`) |
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Could you move this 2.2.0.rst?
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| thanks for your reviews! merging then |
cbpygit pushed a commit to cbpygit/pandas that referenced this pull request Jan 2, 2024
…ing a single string value (pandas-dev#56321)
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doc/source/whatsnew/vX.X.X.rstfile if fixing a bug or adding a new feature.