double_edge_swap#

double_edge_swap(G, nswap=1, max_tries=100, seed=None)[source]#

Swap two edges in the graph while keeping the node degrees fixed.

A double-edge swap removes two randomly chosen edges u-v and x-y and creates the new edges u-x and v-y:

u--v            u  v
       becomes  |  |
x--y            x  y

If either the edge u-x or v-y already exist no swap is performed and another attempt is made to find a suitable edge pair.

Parameters:

Ggraph: An undirected graph
nswapinteger (optional, default=1): Number of double-edge swaps to perform
max_triesinteger (optional): Maximum number of attempts to swap edges
seedinteger, random_state, or None (default): Indicator of random number generation state. See Randomness.

Returns:

Raises:

NetworkXError: If G is directed, or If nswap > max_tries, or If there are fewer than 4 nodes or 2 edges in G.
NetworkXAlgorithmError: If the number of swap attempts exceeds max_tries before nswap swaps are made

Notes

Does not enforce any connectivity constraints.

The graph G is modified in place.