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DOC: Add comment about inplace/copy proposal #51487

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DOC: Add comment about inplace/copy proposal
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15 changes: 15 additions & 0 deletions doc/source/getting_started/comparison/includes/copies.rst
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Expand Up @@ -11,3 +11,18 @@ or overwrite the original one:
.. code-block:: python

df = df.sort_values("col1")

.. note::

You will see an ``inplace=True`` or ``copy=False`` keyword argument available for
some methods:

.. code-block:: python

df.replace(5, inplace=True)
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I don't think replace is a good example. We are keeping inplace there.

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That’s why I am using it. I could add an explicit comment that replace is one of the few methods where we are keeping it

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Added a small note that replace might keep inplace

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Thanks, it might be good to also give an example of something that would lose inplace, for comparison's sake.

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What would you want to show with it? I am struggling to come up with an explanation for such an example

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I don't think we would need to go to in detail, just say e.g.

"Some methods cannot operate inplace (e.g. reindex), or would already avoid copying the data with Copy on Write. (e.g. rename)

It is recommended that the inplace/copy parameters be avoided for those methods".

No big deal if we don't add this, though, since people can always read the PDEP.

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Ah got you, I thought you wanted to add a code example.

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I'll leave the suggestion to not use them out. When used in the appropriate context it can speed up your code. I think it's clear enough that users can figure the consequences out for themself.


There is an active discussion about deprecating and removing ``inplace`` and ``copy`` for
most methods (e.g. ``dropna``) except for a very small subset of methods
(including ``replace``). Both keywords won't be
necessary anymore in the context of Copy-on-Write. The proposal can be found
[here](https://github.com/pandas-dev/pandas/pull/51466).
9 changes: 9 additions & 0 deletions doc/source/whatsnew/v2.0.0.rst
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Expand Up @@ -818,6 +818,14 @@ Other API changes
- Added :func:`pandas.api.types.is_any_real_numeric_dtype` to check for real numeric dtypes (:issue:`51152`)
-

.. note::

A current PDEP proposes the deprecation and removal of the keywords ``inplace`` and ``copy``
for all but a small subset of methods from the pandas API. The current discussion takes place
at [here](https://github.com/pandas-dev/pandas/pull/51466). The keywords won't be necessary
anymore in the context of Copy-on-Write. If this proposal is accepted, both
keywords would be deprecated in the next release of pandas and removed in pandas 3.0.

.. ---------------------------------------------------------------------------
.. _whatsnew_200.deprecations:

Expand Down Expand Up @@ -1423,6 +1431,7 @@ Metadata

Other
^^^^^

- Bug in :meth:`Series.searchsorted` inconsistent behavior when accepting :class:`DataFrame` as parameter ``value`` (:issue:`49620`)
- Bug in :func:`array` failing to raise on :class:`DataFrame` inputs (:issue:`51167`)
-
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