cdlib: Error converting graphs - cannot add edges, Invalid vertex id

Describe the bug I have received the “InternalError: Error at type_indexededgelist.c:272: cannot add edges, Invalid vertex id” error trying to use the method algorithms.angel. I have a nx undirected weighted graph, created from a pandas data frame, and think that the error is in __from_nx_to_igraph at utils.py

To Reproduce my graph: g = nx.from_pandas_edgelist(df, 'source', 'target', 'weight') When I try to see my edges: list(g.edges()) I receive: [(21198069, 28883519), (21198069, 28667573), (21198069, 26440037), ... ] To see the weight of an edge: g.edges[21198069, 28883519] Output: {'weight': 9} When I try to get the communities with the command: coms = algorithms.angel(g, min_community_size=4, threshold=0.25) I get the error:

InternalError                             Traceback (most recent call last)
<ipython-input-132-44b171f02346> in <module>
      1 #coms = algorithms.big_clam(g, 5)
----> 2 coms = algorithms.angel(g, min_community_size=4, threshold=0.25)

/opt/conda/lib/python3.6/site-packages/cdlib/algorithms/overlapping_partition.py in angel(g, threshold, min_community_size)
    120         raise ModuleNotFoundError("Optional dependency not satisfied: install igraph to use the selected feature.")
    121 
--> 122     g = convert_graph_formats(g, ig.Graph)
    123     with suppress_stdout():
    124         a = Angel(graph=g, min_comsize=min_community_size, threshold=threshold, save=False)

/opt/conda/lib/python3.6/site-packages/cdlib/utils.py in convert_graph_formats(graph, desired_format, directed)
    122         return __from_igraph_to_nx(graph, directed)
    123     elif ig is not None and desired_format is ig.Graph:
--> 124         return __from_nx_to_igraph(graph, directed)
    125     else:
    126         raise TypeError("The graph object should be either a networkx or an igraph one.")

/opt/conda/lib/python3.6/site-packages/cdlib/utils.py in __from_nx_to_igraph(g, directed)
     79     gi = ig.Graph(directed=directed)
     80     gi.add_vertices(list(g.nodes()))
---> 81     gi.add_edges(list(g.edges()))
     82     return gi
     83 

/opt/conda/lib/python3.6/site-packages/igraph/__init__.py in add_edges(self, es)
    253           endpoints. Vertices are enumerated from zero.
    254         """
--> 255         return GraphBase.add_edges(self, es)
    256 
    257     def add_vertex(self, name=None, kwds):

InternalError: Error at type_indexededgelist.c:272: cannot add edges, Invalid vertex id

• CDlib version cdlib-0.1.7
• Operating System mac os 10.12.5
• Python version 3.6
• Version(s) of CDlib required libraries

Additional context I’m using jupyter notebook