DOC Remove experimental tag from ColumnTransformer (scikit-learn#13835)

Author: qinhanmin2014

doc/whats_new/v0.21.rst

@@ -121,6 +121,12 @@ Support for Python 3.4 and below has been officially dropped.
   parameter which can be used to find the clusters instead of ``n_clusters``.
   :issue:`9069` by :user:`Vathsala Achar <VathsalaAchar>` and `Adrin Jalali`_.
 
+:mod:`sklearn.compose`
+......................
+
+- |API| :class:`compose.ColumnTransformer` is no longer an experimental
+  feature. :pr:`13835` by :user:`Hanmin Qin <qinhanmin2014>`.
+
 :mod:`sklearn.datasets`
 .......................
 

sklearn/compose/_column_transformer.py

@@ -33,9 +33,6 @@
 class ColumnTransformer(_BaseComposition, TransformerMixin):
     """Applies transformers to columns of an array or pandas DataFrame.
 
-    EXPERIMENTAL: some behaviors may change between releases without
-    deprecation.
-
     This estimator allows different columns or column subsets of the input
     to be transformed separately and the features generated by each transformer
     will be concatenated to form a single feature space.

sklearn/datasets/openml.py

@@ -449,9 +449,8 @@ def fetch_openml(name=None, version='active', data_id=None, data_home=None,
 
     .. note:: EXPERIMENTAL
 
-        The API is experimental in version 0.20 (particularly the return value
-        structure), and might have small backward-incompatible changes in
-        future releases.
+        The API is experimental (particularly the return value structure),
+        and might have small backward-incompatible changes in future releases.
 
     Parameters
     ----------
@@ -515,10 +514,9 @@ def fetch_openml(name=None, version='active', data_id=None, data_home=None,
 
         .. note:: EXPERIMENTAL
 
-            This interface is **experimental** as at version 0.20 and
-            subsequent releases may change attributes without notice
-            (although there should only be minor changes to ``data``
-            and ``target``).
+            This interface is **experimental** and subsequent releases may
+            change attributes without notice (although there should only be
+            minor changes to ``data`` and ``target``).
 
         Missing values in the 'data' are represented as NaN's. Missing values
         in 'target' are represented as NaN's (numerical target) or None