Convert NLTK dependency graph to Tikz drawing

nltk_to_tikz.py

def as_tikz_graph(graph):
    """Converts an nltk.parse.dependencygraph.DependencyGraph object to a Tikz
    drawing.

    :graph: An NLTK dependency graph.
    :returns: A string containing the LaTeX code to draw the graph with the
    tikz-dependency package.
    """
    nodes = graph.nodelist

    template = """\\begin{{dependency}}
    \\begin{{deptext}}[column sep=0.5cm]
        {deptext}
    \\end{{deptext}}
{depedges}
\\end{{dependency}}"""
    deptext = ' \\& '.join([node['word'] for node in nodes
                            if node['word'] is not None]) + ' \\\\'

    edge_template = '\\depedge{{{origin}}}{{{dest}}}{{{rel}}}'
    root_node_template = '\\deproot{{{dest}}}{{root}}'

    def edge_as_string(node):
        if node['rel'] == 'null':
            return root_node_template.format(dest=node['address'])

        return edge_template.format(origin=node['head'],
                                    dest=node['address'],
                                    rel=node['rel'])

    depedges = '\n'.join(['    ' + edge_as_string(edge) for edge in nodes
                          if edge['rel'] != 'TOP'])

    return template.format(deptext=deptext, depedges=depedges)