when calling sklearn.tree.export.export_graphviz() I encountered this error:

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
E:\Anaconda3\envs\fastai\lib\site-packages\graphviz\backend.py in run(cmd,
 
 input, capture_output, check, quiet, **kwargs)
    146     try:
--> 147         proc = subprocess.Popen(cmd, startupinfo=get_startupinfo(), **kwargs)
    148     except OSError as e:

E:\Anaconda3\envs\fastai\lib\subprocess.py in __init__(self, args, bufsize, executable, stdin, stdout, stderr, preexec_fn,
 
 close_fds, shell, cwd, env, universal_newlines, startupinfo, creationflags, restore_signals, start_new_session, pass_fds, encoding, errors)
    708                                 errread, errwrite,
--> 709                                 restore_signals, start_new_session)
    710         except:

E:
 
\Anaconda3\envs\fastai\lib\subprocess.py in _execute_child(self, args, executable, preexec_fn, close_fds, pass_fds, cwd, env, startupinfo, creationflags, shell, p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite, unused_restore_signals, unused_start_new_session)
    996                                          os.fspath(cwd) if cwd is not None else None,
--> 997                                          startupinfo)
    998             finally:

FileNotFoundError: [WinError 2] 系統找不到指定的檔案。

During handling of the above exception, another exception occurred:

ExecutableNotFound                        Traceback (most recent call last)
E:\Anaconda3\envs\fastai\lib\site-packages\IPython\core\formatters.py in __call__(self, obj)
    343             method = get_real_method(obj, self.print_method)
    344             if method is not None:
--> 345                 return method()
    346             return None
    347         else:

E:\Anaconda3\envs\fastai\lib\site-packages\graphviz\files.py in _repr_svg_(self)
    104 
    105     def _repr_svg_(self):
--> 106         return self.pipe(format='svg').decode(self._encoding)
    107 
    108     def pipe(self, format=None, renderer=None, formatter=None):

E:\Anaconda3\envs\fastai\lib\site-packages\graphviz\files.py in pipe(self, format, renderer, formatter)
    126         data = text_type(self.source).encode(self._encoding)
    127 
--> 128         out = backend.pipe(self._engine, format, data, renderer, formatter)
    129 
    130         return out

E:\Anaconda3\envs\fastai\lib\site-packages\graphviz\backend.py in pipe(engine, format, data, renderer, formatter, quiet)
    204     """
    205     cmd, _ = command(engine, format, None, renderer, formatter)
--> 206     out, _ = run(cmd, input=data, capture_output=True, check=True, quiet=quiet)
    207     return out
    208 

E:\Anaconda3\envs\fastai\lib\site-packages\graphviz\backend.py in run(cmd, input, capture_output, check, quiet, **kwargs)
    148     except OSError as e:
    149         if e.errno == errno.ENOENT:
--> 150             raise ExecutableNotFound(cmd)
    151         else:  # pragma: no cover
    152             raise

ExecutableNotFound: failed to execute ['dot', '-Tsvg'], make sure the Graphviz executables are on your systems' PATH

I’ve tried to import graphviz but it failed

---------------------------------------------------------------------------
ModuleNotFoundError                       Traceback (most recent call last)
<ipython-input-1-f7133d3517ab> in <module>
----> 1 import graphviz

ModuleNotFoundError: No module named 'graphviz'

Following this, I pip install graphviz after conda install graphviz (prior error occurs after only conda install the library) But I still failed.