DOC Added the meaning of the default=None case in SparsePCA
@@ -23,7 +23,8 @@ class SparsePCA(TransformerMixin, BaseEstimator):
Parameters
----------
n_components : int, default=None
- Number of sparse atoms to extract.
+ Number of sparse atoms to extract. If None, then ``n_components``
+ is set to ``n_features_in_``.
alpha : float, default=1
Sparsity controlling parameter. Higher values lead to sparser
