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networkx.classes.function.is_negatively_weighted

is_negatively_weighted(G, edge=None, weight='weight')[source]

Returns True if G has negatively weighted edges.

Parameters:
  • G (graph) – A NetworkX graph.
  • edge (tuple, optional) – A 2-tuple specifying the only edge in G that will be tested. If None, then every edge in G is tested.
  • weight (string, optional) – The attribute name used to query for edge weights.
Returns:

A boolean signifying if G, or the specified edge, is negatively weighted.
Return type:

bool
Raises:

NetworkXError – If the specified edge does not exist.

Examples

>>> G = nx.Graph()
>>> G.add_edges_from([(1, 3), (2, 4), (2, 6)])
>>> G.add_edge(1, 2, weight=4)
>>> nx.is_negatively_weighted(G, (1, 2))
False
>>> G[2][4]['weight'] = -2
>>> nx.is_negatively_weighted(G)
True
>>> G = nx.DiGraph()
>>> edges = [('0', '3', 3), ('0', '1', -5), ('1', '0', -2)]
>>> G.add_weighted_edges_from(edges)
>>> nx.is_negatively_weighted(G)
True