DOC: Fixing EX01 - Added examples (#54267)

* Example ExtensionArray._formatter

* Added if boxed...

Author: DeaMariaLeon

ci/code_checks.sh

@@ -85,7 +85,6 @@ if [[ -z "$CHECK" || "$CHECK" == "docstrings" ]]; then
         pandas.api.extensions.ExtensionDtype \
         pandas.api.extensions.ExtensionArray \
         pandas.arrays.NumpyExtensionArray \
-        pandas.api.extensions.ExtensionArray._formatter \
         pandas.api.extensions.ExtensionArray._from_factorized \
         pandas.api.extensions.ExtensionArray._from_sequence \
         pandas.api.extensions.ExtensionArray._from_sequence_of_strings \

pandas/core/arrays/base.py

@@ -1527,6 +1527,16 @@ def _formatter(self, boxed: bool = False) -> Callable[[Any], str | None]:
             returns a string. By default, :func:`repr` is used
             when ``boxed=False`` and :func:`str` is used when
             ``boxed=True``.
+
+        Examples
+        --------
+        >>> class MyExtensionArray(pd.arrays.NumpyExtensionArray):
+        ...     def _formatter(self, boxed=False):
+        ...         return lambda x: '*' + str(x) + '*' if boxed else repr(x) + '*'
+        >>> MyExtensionArray(np.array([1, 2, 3, 4]))
+        <MyExtensionArray>
+        [1*, 2*, 3*, 4*]
+        Length: 4, dtype: int64
         """
         if boxed:
             return str