DOC Correct description of test_size in GroupShuffleSplit
@@ -1448,10 +1448,13 @@ class GroupShuffleSplit(ShuffleSplit):
test_size : float, int, None, optional (default=None)
If float, should be between 0.0 and 1.0 and represent the proportion
- of the dataset to include in the test split. If int, represents the
- absolute number of test groups. If None, the value is set to the
- complement of the train size. If ``train_size`` is also None, it will
- be set to 0.2.
+ of groups to include in the test split (rounded up). If int,
+ represents the absolute number of test groups. If None, the value is
+ set to the complement of the train size. By default, the value is set
+ to 0.2.
+ The default will change in version 0.21. It will remain 0.2 only
+ if ``train_size`` is unspecified, otherwise it will complement
+ the specified ``train_size``.
train_size : float, int, or None, default is None
If float, should be between 0.0 and 1.0 and represent the
