is_negatively_weighted#

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

Returns True if G has negatively weighted edges.

Parameters:

Ggraph: A NetworkX graph.
edgetuple, 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:

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

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