sklearn.cross_validation.check_cv()

cv : int, cross-validation generator or an iterable, optional

Determines the cross-validation splitting strategy. Possible inputs for cv are:

• None, to use the default 3-fold cross-validation,
• integer, to specify the number of folds.
• An object to be used as a cross-validation generator.
• An iterable yielding train/test splits.

For integer/None inputs, if classifier is True and y is binary or multiclass, StratifiedKFold is used. In all other cases, KFold is used.

Refer User Guide for the various cross-validation strategies that can be used here.

X : array-like

The data the cross-val object will be applied on.

y : array-like

The target variable for a supervised learning problem.

classifier : boolean optional

Whether the task is a classification task, in which case stratified KFold will be used.