代码中需要运行python模块graphviz，安装：
pip install graphviz
运行后报错：
graphviz.backend.execute.ExecutableNotFound: failed to execute PosixPath('dot'), make sure the Graphviz executables are on your systems' PATH
报错的全部信息：
Traceback (most recent call last):
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/site-packages/graphviz/backend/execute.py", line 81, in run_check
proc = subprocess.run(cmd, **kwargs)
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/subprocess.py", line 488, in run
with Popen(*popenargs, **kwargs) as process:
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/subprocess.py", line 800, in __init__
restore_signals, start_new_session)
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/subprocess.py", line 1551, in _execute_child
raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: PosixPath('dot'): PosixPath('dot')
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "cartpole.py", line 76, in <module>
evaluation()
File "cartpole.py", line 56, in evaluation
visualize.draw_net(p.config, winner, True, node_names=node_names)
File "/home/devil/Desktop/neat/visualize.py", line 150, in draw_net
dot.render(filename, view=view)
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/site-packages/graphviz/_tools.py", line 171, in wrapper
return func(*args, **kwargs)
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/site-packages/graphviz/rendering.py", line 122, in render
rendered = self._render(*args, **kwargs)
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/site-packages/graphviz/_tools.py", line 171, in wrapper
return func(*args, **kwargs)
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/site-packages/graphviz/backend/rendering.py", line 327, in render
capture_output=True)
File "/home/devil/anaconda3/envs/tmp2/lib/python3.7/site-packages/graphviz/backend/execute.py", line 84, in run_check
raise ExecutableNotFound(cmd) from e
graphviz.backend.execute.ExecutableNotFound: failed to execute PosixPath('dot'), make sure the Graphviz executables are on your systems' PATH=========================================
解决方法：
sudo apt install graphviz
PS:
原来是没安装绘图的程序，只安装了python的连接模块。
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