如何在sklearn中输出决策树数据

from sklearn import tree
from sklearn.datasets import load_iris
from sklearn.model_selection import train_test_split
from sklearn.tree import export_graphviz

iris = load_iris()
X_train, X_test, y_train, y_test = train_test_split(iris.data, iris.target, test_size=0.2, random_state=42)

clf = tree.DecisionTreeClassifier()
clf.fit(X_train, y_train)

export_graphviz(clf, out_file='tree.dot', feature_names=iris.feature_names, class_names=iris.target_names, filled=True, rounded=True)