More convenient networkx -> abp conversion

Now you can write `abp.fancy.GraphState(nx.Graph())`.
TODO: make this work for a non-fancy `GraphState`

abp/fancy.py

@@ -10,7 +10,8 @@ import util
 
 class GraphState(graphstate.GraphState, nx.Graph):
     def __init__(self, *args, **kwargs):
-        if type(args[0])==nx.Graph:
+        if args and type(args[0]) == nx.Graph:
+            graphstate.GraphState.__init__(self)
             self.from_nx(args[0])
         else:
             graphstate.GraphState.__init__(self, *args, **kwargs)

tests/test_fancy.py

@@ -5,6 +5,7 @@ from abp import clifford
 from abp.util import xyz
 from mock import simple_graph
 
+
 def test_json_basic():
     """ Test that we can export to JSON """
     g = simple_graph()
@@ -12,6 +13,7 @@ def test_json_basic():
     assert "adj" in js
     assert "node" in js
 
+
 def test_tuple_keys():
     """ Test that we can use tuple-ish keys """
     g = fancy.GraphState()
@@ -20,17 +22,22 @@ def test_tuple_keys():
     g.add_edge((1, 2, 3), "string")
     json.dumps(g.to_json(True))
 
+
 def networkx_test():
     """ Test that fancy graph states really behave like networkx graphs """
     g = fancy.GraphState()
-    g.add_qubit(0, position = xyz(10, 0, 0))
-    g.add_qubit(1, position = xyz(1, 0, 0))
+    g.add_qubit(0, position=xyz(10, 0, 0))
+    g.add_qubit(1, position=xyz(1, 0, 0))
     g.act_hadamard(0)
     g.act_hadamard(1)
     g.act_cz(0, 1)
     g.copy()
 
-    # TODO: more tests here!
-
-
 
+def test_from_nx():
+    """ Test that making graphs from networkx objects goes smoothly """
+    g = nx.random_geometric_graph(100, 2)
+    psi = fancy.GraphState(g)
+    assert psi.node[0]["vop"] == 0
+    assert len(psi.edges()) > 0
+    psi.measure(0, "px", detail=True)