error with plot_animal_tree

[vnitinv]

import mglearn
mglearn.plots.plot_animal_tree()

error log

/opt/anaconda3/lib/python3.7/site-packages/sklearn/externals/six.py:31: DeprecationWarning: The module is deprecated in version 0.21 and will be removed in version 0.23 since we've dropped support for Python 2.7. Please rely on the official version of six (https://pypi.org/project/six/).
  "(https://pypi.org/project/six/).", DeprecationWarning)
/opt/anaconda3/lib/python3.7/site-packages/sklearn/externals/joblib/__init__.py:15: DeprecationWarning: sklearn.externals.joblib is deprecated in 0.21 and will be removed in 0.23. Please import this functionality directly from joblib, which can be installed with: pip install joblib. If this warning is raised when loading pickled models, you may need to re-serialize those models with scikit-learn 0.21+.
  warnings.warn(msg, category=DeprecationWarning)
---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
/opt/anaconda3/lib/python3.7/site-packages/graphviz/backend.py in run(cmd, input, capture_output, check, quiet, **kwargs)
    158     try:
--> 159         proc = subprocess.Popen(cmd, startupinfo=get_startupinfo(), **kwargs)
    160     except OSError as e:

/opt/anaconda3/lib/python3.7/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, text)
    774                                 errread, errwrite,
--> 775                                 restore_signals, start_new_session)
    776         except:

/opt/anaconda3/lib/python3.7/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, restore_signals, start_new_session)
   1521                             err_msg += ': ' + repr(err_filename)
-> 1522                     raise child_exception_type(errno_num, err_msg, err_filename)
   1523                 raise child_exception_type(err_msg)

FileNotFoundError: [Errno 2] No such file or directory: 'dot': 'dot'

During handling of the above exception, another exception occurred:

ExecutableNotFound                        Traceback (most recent call last)
<ipython-input-2-53d3a20defda> in <module>
      1 import mglearn
----> 2 mglearn.plots.plot_animal_tree()

/opt/anaconda3/lib/python3.7/site-packages/mglearn/plot_animal_tree.py in plot_animal_tree(ax)
     23     mygraph.edge("2", "5", label="True")
     24     mygraph.edge("2", "6", label="False")
---> 25     mygraph.render("tmp")
     26     ax.imshow(imread("tmp.png"))
     27     ax.set_axis_off()

/opt/anaconda3/lib/python3.7/site-packages/graphviz/files.py in render(self, filename, directory, view, cleanup, format, renderer, formatter, quiet, quiet_view)
    207         rendered = backend.render(self._engine, format, filepath,
    208                                   renderer=renderer, formatter=formatter,
--> 209                                   quiet=quiet)
    210 
    211         if cleanup:

/opt/anaconda3/lib/python3.7/site-packages/graphviz/backend.py in render(engine, format, filepath, renderer, formatter, quiet)
    204     else:
    205         cwd = None
--> 206     run(cmd, capture_output=True, cwd=cwd, check=True, quiet=quiet)
    207     return rendered
    208 

/opt/anaconda3/lib/python3.7/site-packages/graphviz/backend.py in run(cmd, input, capture_output, check, quiet, **kwargs)
    160     except OSError as e:
    161         if e.errno == errno.ENOENT:
--> 162             raise ExecutableNotFound(cmd)
    163         else:
    164             raise

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

[vnitinv]

pip list o/p:

mglearn                            0.1.7  
graphviz                           0.13.2

[vnitinv]

Fixed with

brew install graphviz

[amueller]

Sorry, this might indeed be a bit tricky right now. I might want to just have the image in the notebook instead.
I'll reopen this issue so I can fix that for the next print of the book.