Morteza R Morteza R - 1 year ago 420
Python Question

Graphviz's executables are not found (Python 3.4)

I am running Python3.4 on Windows 7. I am trying to use the Python interface for graphviz. This is a script I intend to run:

from graphviz import Digraph
import pydotplus

dot = Digraph(comment='The Round Table')

dot.node('A', 'King Arthur')
dot.node('B', 'Sir Bedevere the Wise')
dot.node('L', 'Sir Lancelot the Brave')
dot.edges(['AB', 'AL'])
dot.edge('B', 'L', constraint='false')

dot.render('test-output/round-table.gv', view=True)

I get the following error at runtime:

RuntimeError: failed to execute ['dot', '-Tpdf', '-O', 'test-output/round-table.gv'], make sure the Graphviz executables are on your systems' path

Now I am sure I have properly installed the correct dependencies. I first tried to set the correct environment variables. The graphviz executables are located at C:\Program Files (x86)\Graphviz2.37\bin so I went to the Environment Variables section. There are two sections there: User Variables and System Variables. Under System Variables I clicked on Path and then clicked
and added ;C:\Program Files (x86)\Graphviz2.37\bin to the end of the string and saved. This didn't clear the error.

Then, following the answer given here I uninstalled pydot (actually I use pydotplus here) and re-installed it again, but still no success.

I have been trying for hours to fix this and the whole PATH variable thing is just confusing and frustrating.

Answer Source

As it appears, Graphviz2.37 is known to have problems with the PATH variable on windows. I uninstalled it, removed the environment variables associated with it and instead downloaded and installed the newer beta version from here and it now works like a charm.

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