在python中有效地找到图中每个节点的n环

Question

我有一个M边缘定义的numpy数组，它是Mx2并包含节点索引。对于每个节点，我想在节点的n环（在我的例子中为3环）内找到边缘。对于商业模型，我有一个中等密度计算网格的N = 250K节点，所以我正在寻找适当有效和稀疏的东西。

Answer 1

import numpy as np
import networkx as nx
G = nx.dorogovtsev_goltsev_mendes_graph(4)
edges_list = G.edges()
edges_list = np.array(edges_list)
one_ring = []
for n in G.nodes():
    first = edges_list[edges_list[:, 0] == n, 1]
    second = edges_list[edges_list[:, 1] == n, 0]
    one_ring.append(np.hstack([first, second]))
N = 3
n_ring = []
def find_n_ring(root, node, i):
    if i >= N:
        return node
    for node2 in one_ring[node]:
        n_ring_node = find_n_ring(root, node2, i + 1)
        if n_ring_node is not None and n_ring_node not in n_ring[root]:
            n_ring[root].append(n_ring_node)
for root in G.nodes():
    n_ring.append([])
    find_n_ring(root, root, 0)
print(n_ring)