Graphviz executables not found
Question: I'm familiar with the various threads that already exist regarding this
problem.

I'm on a Windows 7 machine. I'm just trying to run the example code to draw a
decision tree:

    
    
    from sklearn.datasets import load_iris
    from sklearn import tree
    clf = tree.DecisionTreeClassifier()
    iris = load_iris()
    clf = clf.fit(iris.data, iris.target)
    
    from sklearn.externals.six import StringIO
    import pydotplus
    
    dot_data = StringIO() 
    tree.export_graphviz(clf, out_file=dot_data) 
    graph = pydotplus.graph_from_dot_data(dot_data.getvalue()) 
    graph.write_pdf("iris.pdf") 
    

I installed graphviz and added it as a PATH variable. I installed pydot (now
pydotplus) after installing the python's graphviz library. I still get the
error:

    
    
    InvocationException: GraphViz's executables not found
    


Answer: [It looks like the installer isn't setting the PATH variable for
you](http://www.graphviz.org/Download_windows.php), you'll need to add the
installation folder of Graphviz to your PATH manually.

