Copies

Most pandas operations return copies of the Series/DataFrame. To make the changes "stick", you'll need to either assign to a new variable:

.. code-block:: python

  sorted_df = df.sort_values("col1")

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)

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>_.