This documents an unmaintained version of NetworkX. Please upgrade to a maintained version and see the current NetworkX documentation.


set_edge_attributes(G, values, name=None)[source]

Sets edge attributes from a given value or dictionary of values.


The call order of arguments values and name switched between v1.x & v2.x.

  • G (NetworkX Graph)

  • values (scalar value, dict-like) – What the edge attribute should be set to. If values is not a dictionary, then it is treated as a single attribute value that is then applied to every edge in G. This means that if you provide a mutable object, like a list, updates to that object will be reflected in the edge attribute for each edge. The attribute name will be name.

    If values is a dict or a dict of dict, it should be keyed by edge tuple to either an attribute value or a dict of attribute key/value pairs used to update the edge’s attributes. For multigraphs, the edge tuples must be of the form (u, v, key), where u and v are nodes and key is the edge key. For non-multigraphs, the keys must be tuples of the form (u, v).

  • name (string (optional, default=None)) – Name of the edge attribute to set if values is a scalar.


After computing some property of the edges of a graph, you may want to assign a edge attribute to store the value of that property for each edge:

>>> G = nx.path_graph(3)
>>> bb = nx.edge_betweenness_centrality(G, normalized=False)
>>> nx.set_edge_attributes(G, bb, 'betweenness')
>>> G.edges[1, 2]['betweenness']

If you provide a list as the second argument, updates to the list will be reflected in the edge attribute for each edge:

>>> labels = []
>>> nx.set_edge_attributes(G, labels, 'labels')
>>> labels.append('foo')
>>> G.edges[0, 1]['labels']
>>> G.edges[1, 2]['labels']

If you provide a dictionary of dictionaries as the second argument, the entire dictionary will be used to update edge attributes:

>>> G = nx.path_graph(3)
>>> attrs = {(0, 1): {'attr1': 20, 'attr2': 'nothing'},
...          (1, 2): {'attr2': 3}}
>>> nx.set_edge_attributes(G, attrs)
>>> G[0][1]['attr1']
>>> G[0][1]['attr2']
>>> G[1][2]['attr2']