StrattifiedFold Example

from sklearn.model_selection import StratifiedKFold
from sklearn.base import clone

skfolds = StratifiedKFold(n_splits =3,random_state=42)

for train_index,test_index in skfolds.split(X_train,y_train_5):
  clone_clf = clone(sgd_clf)
  X_train_folds = X_train[train_index]
  y_train_folds = y_train_5[train_index]
  X_test_fold = X_train[test_index]
  y_test_fold = y_train_5[test_index]
  clone_clf.fit(X_train_folds,y_train_folds)
  y_pred = clone_clf.predict(X_test_fold)
  n_correct = sum(y_pred == y_test_fold)
  print(n_correct/len(y_pred))