DOC: Fixing EX01 - Added examples (pandas-dev#54354)

* Example for deregister

* correcting deregister example

Author: DeaMariaLeon

ci/code_checks.sh

@@ -64,7 +64,6 @@ if [[ -z "$CHECK" || "$CHECK" == "docstrings" ]]; then
     MSG='Partially validate docstrings (EX01)' ;  echo $MSG
     $BASE_DIR/scripts/validate_docstrings.py --format=actions --errors=EX01 --ignore_functions \
         pandas.io.stata.StataWriter.write_file \
-        pandas.plotting.deregister_matplotlib_converters \
         pandas.api.extensions.ExtensionArray \
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 

pandas/plotting/_misc.py

@@ -124,6 +124,29 @@ def deregister() -> None:
     --------
     register_matplotlib_converters : Register pandas formatters and converters
         with matplotlib.
+
+    Examples
+    --------
+    .. plot::
+       :context: close-figs
+
+        The following line is done automatically by pandas so
+        the plot can be rendered:
+
+        >>> pd.plotting.register_matplotlib_converters()
+
+        >>> df = pd.DataFrame({'ts': pd.period_range('2020', periods=2, freq='M'),
+        ...                    'y': [1, 2]
+        ...                    })
+        >>> plot = df.plot.line(x='ts', y='y')
+
+    Unsetting the register manually an error will be raised:
+
+    >>> pd.set_option("plotting.matplotlib.register_converters",
+    ...               False)  # doctest: +SKIP
+    >>> df.plot.line(x='ts', y='y')  # doctest: +SKIP
+    Traceback (most recent call last):
+    TypeError: float() argument must be a string or a real number, not 'Period'
     """
     plot_backend = _get_plot_backend("matplotlib")
     plot_backend.deregister()