sklearn.cross_validation.StratifiedShuffleSplit¶
- class sklearn.cross_validation.StratifiedShuffleSplit(y, n_iter=10, test_size=0.1, train_size=None, indices=True, random_state=None, n_iterations=None)¶
Stratified ShuffleSplit cross validation iterator
Provides train/test indices to split data in train test sets.
This cross-validation object is a merge of StratifiedKFold and ShuffleSplit, which returns stratified randomized folds. The folds are made by preserving the percentage of samples for each class.
Note: like the ShuffleSplit strategy, stratified random splits do not guarantee that all folds will be different, although this is still very likely for sizeable datasets.
Parameters : y : array, [n_samples]
Labels of samples.
n_iter : int (default 10)
Number of re-shuffling & splitting iterations.
test_size : float (default 0.1), int, or 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 automatically set to the complement of the train size.
train_size : float, int, or None (default is 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.
indices : boolean, optional (default True)
Return train/test split as arrays of indices, rather than a boolean mask array. Integer indices are required when dealing with sparse matrices, since those cannot be indexed by boolean masks.
random_state : int or RandomState
Pseudo-random number generator state used for random sampling.
Examples
>>> from sklearn.cross_validation import StratifiedShuffleSplit >>> X = np.array([[1, 2], [3, 4], [1, 2], [3, 4]]) >>> y = np.array([0, 0, 1, 1]) >>> sss = StratifiedShuffleSplit(y, 3, test_size=0.5, random_state=0) >>> len(sss) 3 >>> print(sss) StratifiedShuffleSplit(labels=[0 0 1 1], n_iter=3, ...) >>> for train_index, test_index in sss: ... print("TRAIN:", train_index, "TEST:", test_index) ... X_train, X_test = X[train_index], X[test_index] ... y_train, y_test = y[train_index], y[test_index] TRAIN: [1 2] TEST: [3 0] TRAIN: [0 2] TEST: [1 3] TRAIN: [0 2] TEST: [3 1]
- __init__(y, n_iter=10, test_size=0.1, train_size=None, indices=True, random_state=None, n_iterations=None)¶