56 lines
1.8 KiB
Python
56 lines
1.8 KiB
Python
|
# Copyright 2014 "cheebee7i".
|
||
|
|
# Copyright 2014 "alexbrc".
|
||
|
|
# Copyright 2014 Jeffrey Finkelstein <jeffrey.finkelstein@gmail.com>.
|
||
|
|
"""Unit tests for the :mod:`networkx.generators.expanders` module.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
import networkx as nx
|
||
|
|
from networkx import adjacency_matrix
|
||
|
|
from networkx import number_of_nodes
|
||
|
|
from networkx.generators.expanders import chordal_cycle_graph
|
||
|
|
from networkx.generators.expanders import margulis_gabber_galil_graph
|
||
|
|
|
||
|
|
import pytest
|
||
|
|
|
||
|
|
|
||
|
|
def test_margulis_gabber_galil_graph():
|
||
|
|
for n in 2, 3, 5, 6, 10:
|
||
|
|
g = margulis_gabber_galil_graph(n)
|
||
|
|
assert number_of_nodes(g) == n * n
|
||
|
|
for node in g:
|
||
|
|
assert g.degree(node) == 8
|
||
|
|
assert len(node) == 2
|
||
|
|
for i in node:
|
||
|
|
assert int(i) == i
|
||
|
|
assert 0 <= i < n
|
||
|
|
|
||
|
|
np = pytest.importorskip("numpy")
|
||
|
|
scipy = pytest.importorskip("scipy")
|
||
|
|
scipy.linalg = pytest.importorskip("scipy.linalg")
|
||
|
|
# Eigenvalues are already sorted using the scipy eigvalsh,
|
||
|
|
# but the implementation in numpy does not guarantee order.
|
||
|
|
w = sorted(scipy.linalg.eigvalsh(adjacency_matrix(g).A))
|
||
|
|
assert w[-2] < 5 * np.sqrt(2)
|
||
|
|
|
||
|
|
|
||
|
|
def test_chordal_cycle_graph():
|
||
|
|
"""Test for the :func:`networkx.chordal_cycle_graph` function."""
|
||
|
|
primes = [3, 5, 7, 11]
|
||
|
|
for p in primes:
|
||
|
|
G = chordal_cycle_graph(p)
|
||
|
|
assert len(G) == p
|
||
|
|
# TODO The second largest eigenvalue should be smaller than a constant,
|
||
|
|
# independent of the number of nodes in the graph:
|
||
|
|
#
|
||
|
|
# eigs = sorted(scipy.linalg.eigvalsh(adjacency_matrix(G).A))
|
||
|
|
# assert_less(eigs[-2], ...)
|
||
|
|
#
|
||
|
|
|
||
|
|
|
||
|
|
def test_margulis_gabber_galil_graph_badinput():
|
||
|
|
pytest.raises(nx.NetworkXError, margulis_gabber_galil_graph, 3,
|
||
|
|
nx.DiGraph())
|
||
|
|
pytest.raises(nx.NetworkXError, margulis_gabber_galil_graph, 3,
|
||
|
|
nx.Graph())
|