MultiGraph.get_edge_data#

MultiGraph.get_edge_data(u, v, key=None, default=None)[source]#

Returns the attribute dictionary associated with edge (u, v, key).

If a key is not provided, returns a dictionary mapping edge keys to attribute dictionaries for each edge between u and v.

This is identical to G[u][v][key] except the default is returned instead of an exception is the edge doesn’t exist.

Parameters:

u, vnodes
defaultany Python object (default=None): Value to return if the specific edge (u, v, key) is not found, OR if there are no edges between u and v and no key is specified.
keyhashable identifier, optional (default=None): Return data only for the edge with specified key, as an attribute dictionary (rather than a dictionary mapping keys to attribute dictionaries).

Returns:

edge_dictdictionary: The edge attribute dictionary, OR a dictionary mapping edge keys to attribute dictionaries for each of those edges if no specific key is provided (even if there’s only one edge between u and v).

Examples

>>> G = nx.MultiGraph()  # or MultiDiGraph
>>> key = G.add_edge(0, 1, key="a", weight=7)
>>> G[0][1]["a"]  # key='a'
{'weight': 7}
>>> G.edges[0, 1, "a"]  # key='a'
{'weight': 7}

Warning: we protect the graph data structure by making G.edges and G[1][2] read-only dict-like structures. However, you can assign values to attributes in e.g. G.edges[1, 2, 'a'] or G[1][2]['a'] using an additional bracket as shown next. You need to specify all edge info to assign to the edge data associated with an edge.

>>> G[0][1]["a"]["weight"] = 10
>>> G.edges[0, 1, "a"]["weight"] = 10
>>> G[0][1]["a"]["weight"]
10
>>> G.edges[1, 0, "a"]["weight"]
10

>>> G = nx.MultiGraph()  # or MultiDiGraph
>>> nx.add_path(G, [0, 1, 2, 3])
>>> G.edges[0, 1, 0]["weight"] = 5
>>> G.get_edge_data(0, 1)
{0: {'weight': 5}}
>>> e = (0, 1)
>>> G.get_edge_data(*e)  # tuple form
{0: {'weight': 5}}
>>> G.get_edge_data(3, 0)  # edge not in graph, returns None
>>> G.get_edge_data(3, 0, default=0)  # edge not in graph, return default
0
>>> G.get_edge_data(1, 0, 0)  # specific key gives back
{'weight': 5}