macos：将点转换为png

Question

我研究了这里列出的解决方案：

• Converting dot to png in python

但是，这些解决方案都不适合我。特别是，当我尝试 check_call 方法时，我收到以下错误：

  File "/Users/anaconda/lib/python2.7/subprocess.py", line 1343, in _execute_child
raise child_exception
  OSError: [Errno 2] No such file or directory

当我使用 pydot 时，我得到这个错误：(graph,)=pydot.graph_from_dot_data(dotfile.getvalue()) TypeError: 'Dot' object is not iterable

这是我在上面的一篇文章中找到的一些示例代码，我一直在测试：

from sklearn import tree  
import pydot
import StringIO
from subprocess import check_call

# Define training and target set for the classifier
train = [[1,2,3],[2,5,1],[2,1,7]]
target = [10,20,30]

# Initialize Classifier. Random values are initialized with always the same random seed of value 0 
# (allows reproducible results)
dectree = tree.DecisionTreeClassifier(random_state=0)
dectree.fit(train, target)

# Test classifier with other, unknown feature vector
test = [2,2,3]
predicted = dectree.predict(test)

dotfile = StringIO.StringIO()
tree.export_graphviz(dectree, out_file=dotfile)
check_call(['dot','-Tpng','InputFile.dot','-o','OutputFile.png'])


(graph,)=pydot.graph_from_dot_data(dotfile.getvalue())
graph.write_png("dtree.png")

提前致谢。

Answer 1

OSError: [Errno 2] No such file or directory 表明 InputFile.dot 可能不存在于您的文件系统中。

如果您只是对将点转换为 png 感兴趣，我创建了一个简单的 python 示例 sample_tree.py，它从在我的 mac 上运行的点文件生成一个 png，

 import pydot
 from subprocess import check_call
 graph = pydot.Dot(graph_type='graph')
 for i in xrange(2):
     edge = pydot.Edge("a", "b%d" % i)
     graph.add_edge(edge)
 graph.write_png('sample_tree.png')

 # If a dot file needs to be created as well
 graph.write_dot('sample_tree.dot')
 check_call(['dot','-Tpng','sample_tree.dot','-o','OutputFile.png'])

顺便说一句，这里也使用了这个 dtree 示例Sckit learn with GraphViz exports empty outputs，以防万一遇到任何其他类似问题。谢谢。