How to connect two nodes if they are disconnected

I use a python NetworkX graph. How to check if 2 nodes are disconnected and then get a new version of the graph where these 2 nodes are connected.

The difference between 2 graphs should have min edit distance (Levenshtein distance)

Before and after for nodes=[1,2]:

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Answer

import networkx as nx

G = nx.DiGraph([(1, 1), (2, 3), (4, 3)])


def check_edge(source, target):
    if not G.has_edge(source, target):
        print('adding edge between {} and {}'.format(source, target))
        G.add_edge(source, target)
    else:
        print('edge exists between {} and {}'.format(source, target))


check_edge(1, 2)
# adding edge between 1 and 2
check_edge(1, 2)
# edge exists between 1 and 2

you can also have a condition to check for an edge of either direction with:

if not G.has_edge(source, target) and not G.has_edge(target, source):