dgl.DGLGraph.edge_id¶

DGLGraph.edge_id(u, v, force_multi=False)¶

Return the edge ID, or an array of edge IDs, between source node u and destination node v.

Parameters:	u (int) – The source node ID. v (int) – The destination node ID. force_multi (bool) – If False, will return a single edge ID if the graph is a simple graph. If True, will always return an array.
Returns:	The edge ID if force_multi == True and the graph is a simple graph. The edge ID array otherwise.
Return type:	int or tensor

Examples

The following example uses PyTorch backend.

For simple graphs:

>>> G = dgl.DGLGraph()
>>> G.add_node(3)
>>> G.add_edges([0, 0], [1, 2]) # (0, 1), (0, 2)
>>> G.edge_id(0, 2)
1
>>> G.edge_id(0, 1)
0

For multigraphs:

>>> G = dgl.DGLGraph(multigraph=True)
>>> G.add_nodes(3)

Adding edges (0, 1), (0, 2), (0, 1), (0, 2), so edge ID 0 and 2 both connect from 0 and 1, while edge ID 1 and 3 both connect from 0 and 2.

>>> G.add_edges([0, 0, 0, 0], [1, 2, 1, 2])
>>> G.edge_id(0, 1)
tensor([0, 2])