networkx.is_negatively_weighted¶

networkx.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:	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()
>>> G.add_weighted_edges_from([('0', '3', 3), ('0', '1', -5), ('1', '0', -2)])
>>> nx.is_negatively_weighted(G)
True