from sklearn.tree import DecisionTreeClassifier
from sklearn.ensemble import AdaBoostClassifier
from sklearn.grid_search import GridSearchCV
param_grid = {'base_estimator__criterion': ['gini', 'entropy'],
    'base_estimator__splitter': ['best', 'random'], 'n_estimators': [1, 2]}
DTC = DecisionTreeClassifier(random_state=11, max_features='auto',
    class_weight='auto', max_depth=None)
ABC = AdaBoostClassifier(base_estimator=DTC)
grid_search_ABC = GridSearchCV(ABC, param_grid=param_grid, scoring='roc_auc')
Using GridSearchCV with AdaBoost and DecisionTreeClassifier