Python TypeError in graph_tool.find_vertex

Question

I wrote a function which creates graph from list of edges (taken from database). I use graph-tool library. Python and this library are quite new for me.

Every vertex in graph should be described, by pair of string and number. In function, if I consider adding new vertex to the graph, first I check if the vertex with same properties exists in the graph. To do this I use find_vertex function. I don't understand why the TypeError occurs, please help. Here you have code of this function and traceback (below):

Edit: One thing more I have to deal with unicode strings.

def make_graph():
    conn = get_connection()
    cursor = conn.cursor()
    cursor.execute(sql) 
    wordnetList = cursor.fetchall()
    g= Graph(directed=False)
    vprop = g.new_vertex_property("python::object")
    g.vertex_properties['lexicalunit'] = vprop
    for (hyponym, v1, hyperonym, v2) in wordnetList: # hyponym and v1 (string and integer respectively) are properties of first vertex, hyperonym and v2 for the second
        matched1 = find_vertex(g, g.vp['lexicalunit'], (hyponym, v1)) # this is line with problem
        if len(matched1) == 0:
            ver1 = g.add_vertex()
            vprop[ver1] = (hyponym, v1)
        elif len(matched1) >= 1:
            ver1 = matched1[0]

        matched2 = find_vertex(g, g.vp['lexicalunit'], (hyperonym, v2))
        if len(matched2) == 0:
            ver2 = g.add_vertex()
            vprop[ver2] = (hyperonym, v2)
        elif len(matched2) >= 1:
            ver2 = matched2[0]

       g.add_edge(ver1, ver2)
   return g

Traceback:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
/home/olorin/Dokumenty/nlp-rr/CRFRelationRecogniser/python/wordnet_explorer/<ipython-input-2-163ed9b92398> in <module>()
----> 1 grf = make_graph()

/home/olorin/Dokumenty/nlp-rr/CRFRelationRecogniser/python/wordnet_explorer/hypgraph.py in make_graph()
     65     for (hyponym, v1, hyperonym, v2) in wordnetList:
     66         print(hyponym, v1, hyperonym, v2)
---> 67         matched1 = find_vertex(g, g.vp['lexicalunit'], (hyponym, v1))
     68         if len(matched1) == 0:
     69             ver1 = g.add_vertex()

/usr/lib/python2.7/dist-packages/graph_tool/util/__init__.pyc in find_vertex(g, prop, match)
     53     can be either a :class:`~graph_tool.PropertyMap` or string with value "in",
     54     "out" or "total", representing a degree type."""
---> 55     val = _convert(prop, match)
     56     ret = libgraph_tool_util.\
     57           find_vertex_range(weakref.ref(g), _degree(g, prop),

/usr/lib/python2.7/dist-packages/graph_tool/__init__.pyc in _convert(prop, val)
    232     if type(vtype) is tuple:
    233         return [vtype[1](x) for x in val]
--> 234     return vtype(val)
    235 
    236 

TypeError: object.__new__() takes no parameters

Answer 1

This is a bug in graph-tool. It has been fixed now in the git version: http://git.skewed.de/graph-tool/commit/?id=566d6dd816e167e1c9e824961537301ee1527e14