feat: use voltage as edge attribute

src/structuregraph_helpers/create.py

@@ -150,7 +150,8 @@ def construct_clean_graph(
         else:
             graph = nx.Graph()
     for u, v, d in structure_graph.graph.edges(data=True):
-        graph.add_edge(u, v, **d)
+        voltage = _voltage(u, v, d["to_jimage"])
+        graph.add_edge(u, v, voltage=voltage)
     for node in graph.nodes:
 
         graph.nodes[node]["specie"] = str(structure_graph.structure[node].specie)
@@ -161,3 +162,19 @@ def construct_clean_graph(
         )
 
     return graph
+
+
+def _voltage(u, v, to_jimage) -> Tuple[int, int, int]:
+    """Voltage is the tuple describing the direction of the edge.
+
+    In simple words, it represents the translation operation.
+
+    Returns:
+        Tuple[int, int, int]: The voltage of the edge.
+    """
+    terms = (u, v)
+    a_image = (0, 0, 0)
+    b_image = to_jimage
+    imags = (a_image, b_image)
+    a_image, b_image = (x for x, _ in sorted(zip(imags, terms), key=lambda x: x[1]))
+    return tuple(a_image[i] - b_image[i] for i in range(3))

src/structuregraph_helpers/hash.py

@@ -24,7 +24,7 @@ def generate_hash(g: nx.Graph, node_decorated: bool, edge_decorated: bool, itera
     if node_decorated:
         node_attr = "specie"
     if edge_decorated:
-        edge_attr = "to_jimage"
+        edge_attr = "voltage"
     return weisfeiler_lehman_graph_hash(
         g, iterations=iterations, edge_attr=edge_attr, node_attr=node_attr
     )

tests/test_create.py

@@ -49,7 +49,7 @@ def test_construct_clean_graph(bcc_graph):
     assert len(graph.edges) == 2
 
     for _, _, d in graph.edges(data=True):
-        assert isinstance(d["to_jimage"], tuple)
+        assert isinstance(d["voltage"], tuple)
 
     for node in graph.nodes:
         assert isinstance(graph.nodes[node]["specie"], str)