Random permutation cross-validator
Yields indices to split data into training and test sets.
Note: contrary to other cross-validation strategies, random splits do not guarantee that all folds will be different, although this is still very likely for sizeable datasets.
Read more in the :ref:`User Guide <cross_validation>`.
Parameters ---------- n_splits : int, default 10 Number of re-shuffling & splitting iterations.
test_size : float, int, None, 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 samples. If None, the value is set to the complement of the train size. If ``train_size`` is also None, it will be set to 0.1.
train_size : float, int, or None, default=None If float, should be between 0.0 and 1.0 and represent the proportion of the dataset to include in the train split. If int, represents the absolute number of train samples. If None, the value is automatically set to the complement of the test size.
random_state : int, RandomState instance or None, optional (default=None) If int, random_state is the seed used by the random number generator; If RandomState instance, random_state is the random number generator; If None, the random number generator is the RandomState instance used by `np.random`.
Examples -------- >>> import numpy as np >>> from sklearn.model_selection import ShuffleSplit >>> X = np.array([1, 2], [3, 4], [5, 6], [7, 8], [3, 4], [5, 6]
) >>> y = np.array(1, 2, 1, 2, 1, 2
) >>> rs = ShuffleSplit(n_splits=5, test_size=.25, random_state=0) >>> rs.get_n_splits(X) 5 >>> print(rs) ShuffleSplit(n_splits=5, random_state=0, test_size=0.25, train_size=None) >>> for train_index, test_index in rs.split(X): ... print("TRAIN:", train_index, "TEST:", test_index) TRAIN: 1 3 0 4
TEST: 5 2
TRAIN: 4 0 2 5
TEST: 1 3
TRAIN: 1 2 4 0
TEST: 3 5
TRAIN: 3 4 1 0
TEST: 5 2
TRAIN: 3 5 1 0
TEST: 2 4
>>> rs = ShuffleSplit(n_splits=5, train_size=0.5, test_size=.25, ... random_state=0) >>> for train_index, test_index in rs.split(X): ... print("TRAIN:", train_index, "TEST:", test_index) TRAIN: 1 3 0
TEST: 5 2
TRAIN: 4 0 2
TEST: 1 3
TRAIN: 1 2 4
TEST: 3 5
TRAIN: 3 4 1
TEST: 5 2
TRAIN: 3 5 1
TEST: 2 4