如何使用 graphviz 绘制树图？

我无法重现一个简单的例子。事情是这样的：

import pandas as pd
import numpy as np
import sklearn as skl
from sklearn import tree
from sklearn.cross_validation import train_test_split as tts



#   import data and give a little overview
sample = pd.read_stata('sample_data.dta')
s = sample

#   Let's learn
X = np.array((s.crisis, s.cash, s.industry, s.current_debt, s.activity)).reshape(1000, 5)
y = np.array(s.wc_measure)

X_train, X_test, y_train, y_test = tts(X, y, test_size = .8)

my_tree = tree.DecisionTreeClassifier()
clf = my_tree.fit(X_train, y_train)
predictions = my_tree.predict(X_test)

#   Graph the tree
from sklearn.externals.six import StringIO  
import pydotplus 
dotfile = StringIO() 
tree.export_graphviz(clf, out_file=dotfile) 
pydotplus.graph_from_dot_data(dotfile.getvalue()).write_png("my_tree.png")

当我尝试绘制树图时，出现以下错误：

pydotplus.graphviz.InvocationException: GraphViz's executables not found

知道问题是什么吗？我完全遵循 graphviz 的文档。

看来你根本没有安装graphviz软件。你应该download http://www.graphviz.org/Download..php并在使用该模块之前安装它。