add option to pass explicitly path to GraphViz executable (useful in Windows 7)

[GoogleCodeExporter]

I am running Windows 7 64-bit. I installed graphviz-2.36.msi from
http://www.graphviz.org/Download_windows.php but I install most programs to
c:\app rather than c:\Program Files, and I get this message (see below). One
problem is that there is no SOFTWARE\ATT registry key anymore. (perhaps related
to https://code.google.com/p/pydot/issues/detail?id=65)

I think the bigger problem is that this discovery mechanism is a cat-and-mouse
game with whatever the graphviz folks do.

===> Could you please add a function so that end-users can just set the
graphviz path manually through whatever mechanism they see fit?

For now I'm just monkeypatching the pydot module:

def force_find_graphviz(graphviz_root):
   binpath = os.path.join(graphviz_root, 'bin')
   programs = 'dot twopi neato circo fdp sfdp'
   def helper():
     for prg in programs.split():
       if os.path.exists(os.path.join(binpath, prg)):
         yield ((prg, os.path.join(binpath, prg)))
       elif os.path.exists(os.path.join(binpath, prg+'.exe')):
         yield ((prg, os.path.join(binpath, prg+'.exe')))
   progdict = dict(helper())
   return lambda: progdict

pydot.find_graphviz = force_find_graphviz('c:/app/util/graphviz/2.36')



C:\tmp\blockdiag>python
Python 2.7.5 |Anaconda 1.9.1 (64-bit)| (default, May 31 2013, 10:45:37) [MSC v.1
500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import pydot
Couldn't import dot_parser, loading of dot files will not be possible.
>>> graph = pydot.Dot(graph_type='graph')
>>> graph.write_png('test.png')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "c:\app\python\anaconda\1.6.0\lib\site-packages\pydot.py", line 1602, in
<lambda>
    lambda path, f=frmt, prog=self.prog : self.write(path, format=f, prog=prog))

  File "c:\app\python\anaconda\1.6.0\lib\site-packages\pydot.py", line 1696, in
write
    dot_fd.write(self.create(prog, format))
  File "c:\app\python\anaconda\1.6.0\lib\site-packages\pydot.py", line 1724, in
create
    self.progs = find_graphviz()
  File "c:\app\python\anaconda\1.6.0\lib\site-packages\pydot.py", line 409, in f
ind_graphviz
    "SOFTWARE\ATT\Graphviz", 0, win32con.KEY_QUERY_VALUE )
pywintypes.error: (2, 'RegOpenKeyEx', 'The system cannot find the file specified
.')
>>>

Original issue reported on code.google.com by jmsa...@gmail.com on 28 Mar 2014 at 7:30

[GoogleCodeExporter]

Hello,

I have windows 7 32 bit and python 2.7

Here how I installed pydot for python

first I installed GraphViz using this link:
http://www.graphviz.org/content/how-install-graphviz-windows-7-i-cant-find-set-file
after that I installed Pyparsing then pydot (from this answer
http://stackoverflow.com/questions/15951748/pydot-and-graphviz-error-couldnt-import-dot-parser-loading-of-dot-files-will)

pip install -Iv https://pypi.python.org/packages/source/p/pyparsing/pyparsing-1.5.7.tar.gz#md5=9be0fcdcc595199c646ab317c1d9a709
pip install pydot

After that when I tried this line of code:

graph.write_png('test.png')

I had a similar error:

File "c:\app\python\anaconda\1.6.0\lib\site-packages\pydot.py", line 409, in find_graphviz
    "SOFTWARE\ATT\Graphviz", 0, win32con.KEY_QUERY_VALUE )
pywintypes.error: (2, 'RegOpenKeyEx', 'The system cannot find the file specified.')

I solved this problem by changing the function find_graphviz() in the pydot.py file, here is the code that I used:

def find_graphviz():
    if os.sys.platform == 'win32':


        if os.environ.has_key('PROGRAMFILES'):
            #Change to your path
            path =  "C:\Program Files\Graphviz2.30\\bin"


        else:

            #Just in case, try the default...
            path = r"C:\Program Files\Graphviz2.30\bin"

        progs = __find_executables(path)

        if progs is not None :

            #print "Used default install location"

            return progs


       return None

Hope it helps.
Cheers

Original comment by sara.ela...@gmail.com on 9 Feb 2015 at 5:29

[KentChun33333]

This saves my day! Thanks : )

[RunshengSong]

Saved my day too!!

[Ben-Gillman]

I'm running Windows 10 with Python 2.7 on the Anaconda Prompt.

I have replaced the def find_graphviz function with your code above.

But when I run Import Pydot, I receive the following error:

      File "C:\Users\...\AppData\Local\Continuum\Anaconda2\lib\site-packages\pydot.py", line 432
        return None
                   ^
      IndentationError: unindent does not match any outer indentation level

This is how I have the function currently defined in pydot.py:

    def find_graphviz():
        if os.sys.platform == 'win32':


        if os.environ.has_key('PROGRAMFILES'):
            #Change to your path
            path =  "C:\Program Files\Graphviz2.30\\bin"


        else:

            #Just in case, try the default...
            path = r"C:\Program Files\Graphviz2.30\bin"

        progs = __find_executables(path)

        if progs is not None :

            #print "Used default install location"

            return progs


        return None

Please let me know how to alleviate this error.

Thank you,
Ben

[johnyf]

The OP suggests that the user be able to pass the path of GraphViz. The standard approach to this problem is to add GraphViz to the path. Hardcoding its path is not a solution #109. Nonetheless, adding an argument graphviz_path to write and its write_* siblings is flexible, and can accommodate also selecting a GraphViz executable from within Python code, in any OS, without modifying the $PATH.

Thanks for the suggestion, this should also provide an alternative for #109, #102, #65 for users that prefer to not change the path.

[johnyf]

Addressed by f3abbd5, which allows passing the path to the desired GraphViz executable as the prog argument of method pydot.Dot.write_* (for example, write_pdf('filename.pdf', prog='C:\\some\\path\\dot.exe'). It remains to test this on Windows.

The mentioned change also implements properly $PATH searching, by using os.environ['PATH'] and the env argument of subprocess.

Relevant discussion and issues:
http://stackoverflow.com/a/5659249/1959808
http://bugs.python.org/issue8557

[jecs89]

I found a manual solution:
sudo apt-get install graphviz

graph.write('test.dot')
dot -Tps test.dot -o outfile.ps

You can the files here: https://github.com/jecs89/LearningEveryDay/tree/master/GP

[johnyf]

Please see #126 (comment)