sklearn.cross_validation.KFold¶
- class sklearn.cross_validation.KFold(n, n_folds=3, indices=None, shuffle=False, random_state=None)¶
K-Folds cross validation iterator.
Provides train/test indices to split data in train test sets. Split dataset into k consecutive folds (without shuffling).
Each fold is then used a validation set once while the k - 1 remaining fold form the training set.
Parameters: n : int
Total number of elements.
n_folds : int, default=3
Number of folds. Must be at least 2.
shuffle : boolean, optional
Whether to shuffle the data before splitting into batches.
random_state : None, int or RandomState
Pseudo-random number generator state used for random sampling. If None, use default numpy RNG for shuffling
See also
- StratifiedKFold
- take label information into account to avoid building
folds, classification
Notes
The first n % n_folds folds have size n // n_folds + 1, other folds have size n // n_folds.
Examples
>>> from sklearn import cross_validation >>> X = np.array([[1, 2], [3, 4], [1, 2], [3, 4]]) >>> y = np.array([1, 2, 3, 4]) >>> kf = cross_validation.KFold(4, n_folds=2) >>> len(kf) 2 >>> print(kf) sklearn.cross_validation.KFold(n=4, n_folds=2, shuffle=False, random_state=None) >>> for train_index, test_index in kf: ... 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: [2 3] TEST: [0 1] TRAIN: [0 1] TEST: [2 3] .. automethod:: __init__
