[Pandas-dev] PDEP-8: In-place methods in pandas (i.e. deprecating the inplace keyword)

[Joris Van den Bossche]

Reminder about this discussion: if there are no more comments, we are
planning to start a vote in a few days.

On Mon, 13 Nov 2023 at 15:53, Joris Van den Bossche <
jorisvandenbossche at gmail.com> wrote:

> Hi list,
>
> There is proposal to deprecate and eventually remove the `inplace` keyword
> (in most places): PDEP-8 (https://github.com/pandas-dev/pandas/pull/51466).
> This has been open for quite a while, and I just updated the text to
> reflect the latest state of the discussion, and wanted to bring this up on
> the mailing list here as well.
>
> Feedback goes to the PR: https://github.com/pandas-dev/pandas/pull/51466
> If you want to see a rendered version of the text:
> https://jorisvandenbossche.github.io/pandas-website-preview/pdeps/0008-inplace-methods-in-pandas.html
> (our website does not yet render them before being merged)
>
> And posting the abstract here as well. The PDEP proposes:
>
>    -
>
>    The inplace parameter will be removed from any method which can never
>    update the underlying values of a pandas object inplace or which alters the
>    shape of the object, and where the inplace=True option is only
>    syntactic sugar for reassigning the result to the calling DataFrame/Series.
>    -
>
>    As a consequence, the inplace parameter is only kept for those methods
>    that can modify the underlying values of a pandas object inplace, such as
>    fillna or replace.
>    -
>
>    With the introduction of Copy-on-Write (PDEP-7[1]
>    <https://jorisvandenbossche.github.io/pandas-website-preview/pdeps/0008-inplace-methods-in-pandas.html#id9>),
>    users don’t need the inplace keyword to avoid a copy of the data.
>    -
>
>    For those methods that will keep the inplace=True option:
>    -
>
>       the method will do an attempt to do the operation inplace but still
>       silently copy when needed (for Copy-on-Write), i.e. there is no guarantee
>       it is actually done inplace.
>       -
>
>       the method will return the calling object (self), instead of the
>       current None.
>
>
> For the full proposal and motivation, see the links above.
>
> Feedback welcome!
>
>
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