Revert "DOC Remove outdated doc in KBinsDiscretizer (scikit-learn#13047)"

Xing · Xing · commit adf689579c9b · 2019-04-28T15:16:38.000-04:00
This reverts commit 5d7fcf3.
diff --git a/sklearn/preprocessing/_discretization.py b/sklearn/preprocessing/_discretization.py
@@ -27,7 +27,12 @@ class KBinsDiscretizer(BaseEstimator, TransformerMixin):
     Parameters
     ----------
     n_bins : int or array-like, shape (n_features,) (default=5)
-        The number of bins to produce. Raises ValueError if ``n_bins < 2``.
+        The number of bins to produce. The intervals for the bins are
+        determined by the minimum and maximum of the input data.
+        Raises ValueError if ``n_bins < 2``.
+
+        If ``n_bins`` is an array, and there is an ignored feature at
+        index ``i``, ``n_bins[i]`` will be ignored.
 
     encode : {'onehot', 'onehot-dense', 'ordinal'}, (default='onehot')
         Method used to encode the transformed result.
@@ -57,7 +62,8 @@ class KBinsDiscretizer(BaseEstimator, TransformerMixin):
     Attributes
     ----------
     n_bins_ : int array, shape (n_features,)
-        Number of bins per feature.
+        Number of bins per feature. An ignored feature at index ``i``
+        will have ``n_bins_[i] == 0``.
 
     bin_edges_ : array of arrays, shape (n_features, )
         The edges of each bin. Contain arrays of varying shapes ``(n_bins_, )``
