使用export_graphviz可视化树报错解决

在使用可视化树的过程中，报错了。说是‘dot.exe’not found in path

原代码：

# import tools needed for visualization
from sklearn.tree import export_graphviz
import pydot

#Pull out one tree from the forest
tree = rf.estimators_[5]

# Export the image to a dot file
export_graphviz(tree, out_file = 'tree.dot', feature_names = features_list, rounded = True, precision = 1)

#Use dot file to create a graph
(graph, ) = pydot.graph_from_dot_file('tree.dot')

# Write graph to a png file
graph.write_png('tree.png');

报错信息：

解决方法：

先使用安装pydot: 

pip install pydot

然后再下载Graphviz（http://www.graphviz.org  选择msi版本）一路安装，记住默认的安装路径

c:\Program Files (x86)\Graphviz2.38\。

将Graphviz2.38添加到环境变量中
 

import os
os.environ['PATH'] = os.environ['PATH'] + (';c:\\Program Files (x86)\\Graphviz2.38\\bin\\')

之后便可以正常使用了。

修改后代码：

# import tools needed for visualization
from sklearn.tree import export_graphviz
import pydot
import os

os.environ['PATH'] = os.environ['PATH'] + (';c:\\Program Files (x86)\\Graphviz2.38\\bin\\')

#Pull out one tree from the forest
tree = rf.estimators_[5]

# Export the image to a dot file
export_graphviz(tree, out_file = 'tree.dot', feature_names = features_list, rounded = True, precision = 1)

#Use dot file to create a graph
(graph, ) = pydot.graph_from_dot_file('tree.dot')

# Write graph to a png file
graph.write_png('tree.png');