### view env/lib/python3.9/site-packages/networkx/algorithms/community/tests/test_kernighan_lin.py @ 0:4f3585e2f14bdraftdefaulttip

author shellac Mon, 22 Mar 2021 18:12:50 +0000
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"""Unit tests for the :mod:`networkx.algorithms.community.kernighan_lin`
module.

"""
import pytest

import networkx as nx
from networkx.algorithms.community import kernighan_lin_bisection
from itertools import permutations

def assert_partition_equal(x, y):
assert set(map(frozenset, x)) == set(map(frozenset, y))

def test_partition():
G = nx.barbell_graph(3, 0)
C = kernighan_lin_bisection(G)
assert_partition_equal(C, [{0, 1, 2}, {3, 4, 5}])

def test_partition_argument():
G = nx.barbell_graph(3, 0)
partition = [{0, 1, 2}, {3, 4, 5}]
C = kernighan_lin_bisection(G, partition)
assert_partition_equal(C, partition)

def test_seed_argument():
G = nx.barbell_graph(3, 0)
C = kernighan_lin_bisection(G, seed=1)
assert_partition_equal(C, [{0, 1, 2}, {3, 4, 5}])

def test_non_disjoint_partition():
with pytest.raises(nx.NetworkXError):
G = nx.barbell_graph(3, 0)
partition = ({0, 1, 2}, {2, 3, 4, 5})
kernighan_lin_bisection(G, partition)

def test_too_many_blocks():
with pytest.raises(nx.NetworkXError):
G = nx.barbell_graph(3, 0)
partition = ({0, 1}, {2}, {3, 4, 5})
kernighan_lin_bisection(G, partition)

def test_multigraph():
G = nx.cycle_graph(4)
M = nx.MultiGraph(G.edges())
M.remove_edge(1, 2)
for labels in permutations(range(4)):
mapping = dict(zip(M, labels))
A, B = kernighan_lin_bisection(nx.relabel_nodes(M, mapping), seed=0)
assert_partition_equal(
[A, B], [{mapping[0], mapping[1]}, {mapping[2], mapping[3]}]
)
```