No write attribute under Python 3?

[elmerehbi]

I have Python 3 through Anaconda.
I tried installing pydot with Anaconda but it returns the following error:

conda install pydot

The following specifications were found to be in conflict:

• pydot
• python 3.5*

So I installed it with pip:
pip install pydot

When I run either of graph.write_pdf("iris.pdf") or Image(graph.create_png()) I get:

list' object has no attribute 'write_pdf' or 'create_png'

Actually there's no "write" attribute to use following the dot: graph.

[johnyf]

The tests are run on Travis under both versions 2 and 3 of Python, so this is likely manipulating an instance of an object that is not a graph, but a list. My guess is that it is a list of graphs, and that it was obtained by loading some dot files. An earlier version of the API used to return a graph object when the dot file defined one graph, and a list of graphs otherwise (in the case of more graphs).

However, I found that the inhomogeneous behavior is more complex (simple is better than complex, PEP 20), so I changed it to return a list in all cases (e.g., a list containing one graph). This simplifies also user code, because there no case distinction needs to be made.

Is this how the list arises? For example, if this is a list containing a single graph, you can obtain the graph with

some_graphs = ...
assert len(some_graphs) == 1, some_graphs
(graph,) = some_graphs
graph.write_pdf('iris.pdf')

[johnyf]

@elmerehbi did this solve the issue?

[elmerehbi]

Thank you for the reply @johnyf.

You got it right, obviously if I am not mistaken. Here's the code I copied a few months ago from the scikit-learn website:

from sklearn.externals.six import StringIO  
import pydot 
dot_data = StringIO() 
tree.export_graphviz(clf, out_file=dot_data) 
graph = pydot.graph_from_dot_data(dot_data.getvalue()) 
graph.write_pdf("iris.pdf") 

from IPython.display import Image  
dot_data = StringIO()  
tree.export_graphviz(clf, out_file=dot_data,  
                         feature_names=iris.feature_names,  
                         class_names=iris.target_names,  
                         filled=True, rounded=True,  
                         special_characters=True)  
graph = pydot.graph_from_dot_data(dot_data.getvalue())  
Image(graph.create_png())

[johnyf]

Indeed, the function pydot.graph_from_dot_data returns what dot_parser.parse_dot_data returns, which is a list.