python sklearn決策樹的圖怎麽畫

from sklearn.datasets import load_iris

from sklearn import tree

iris = load_iris()

clf = tree.DecisionTreeClassifier()

clf = clf.fit(iris.data, iris.target)

from sklearn.externals.six import StringIO

import pydot

dot_data = StringIO()

tree.export_graphviz(clf, out_file=dot_data)

graph = pydot.graph_from_dot_data(dot_data.getvalue())

graph[0].write_dot('iris_simple.dot')

graph[0].write_png('iris_simple.png')