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Diffstat (limited to '.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_wiener.py')
-rw-r--r-- | .venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_wiener.py | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_wiener.py b/.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_wiener.py new file mode 100644 index 00000000..aded9514 --- /dev/null +++ b/.venv/lib/python3.12/site-packages/networkx/algorithms/tests/test_wiener.py @@ -0,0 +1,123 @@ +import networkx as nx + + +def test_wiener_index_of_disconnected_graph(): + assert nx.wiener_index(nx.empty_graph(2)) == float("inf") + + +def test_wiener_index_of_directed_graph(): + G = nx.complete_graph(3) + H = nx.DiGraph(G) + assert (2 * nx.wiener_index(G)) == nx.wiener_index(H) + + +def test_wiener_index_of_complete_graph(): + n = 10 + G = nx.complete_graph(n) + assert nx.wiener_index(G) == (n * (n - 1) / 2) + + +def test_wiener_index_of_path_graph(): + # In P_n, there are n - 1 pairs of vertices at distance one, n - + # 2 pairs at distance two, n - 3 at distance three, ..., 1 at + # distance n - 1, so the Wiener index should be + # + # 1 * (n - 1) + 2 * (n - 2) + ... + (n - 2) * 2 + (n - 1) * 1 + # + # For example, in P_5, + # + # 1 * 4 + 2 * 3 + 3 * 2 + 4 * 1 = 2 (1 * 4 + 2 * 3) + # + # and in P_6, + # + # 1 * 5 + 2 * 4 + 3 * 3 + 4 * 2 + 5 * 1 = 2 (1 * 5 + 2 * 4) + 3 * 3 + # + # assuming n is *odd*, this gives the formula + # + # 2 \sum_{i = 1}^{(n - 1) / 2} [i * (n - i)] + # + # assuming n is *even*, this gives the formula + # + # 2 \sum_{i = 1}^{n / 2} [i * (n - i)] - (n / 2) ** 2 + # + n = 9 + G = nx.path_graph(n) + expected = 2 * sum(i * (n - i) for i in range(1, (n // 2) + 1)) + actual = nx.wiener_index(G) + assert expected == actual + + +def test_schultz_and_gutman_index_of_disconnected_graph(): + n = 4 + G = nx.Graph() + G.add_nodes_from(list(range(1, n + 1))) + expected = float("inf") + + G.add_edge(1, 2) + G.add_edge(3, 4) + + actual_1 = nx.schultz_index(G) + actual_2 = nx.gutman_index(G) + + assert expected == actual_1 + assert expected == actual_2 + + +def test_schultz_and_gutman_index_of_complete_bipartite_graph_1(): + n = 3 + m = 3 + cbg = nx.complete_bipartite_graph(n, m) + + expected_1 = n * m * (n + m) + 2 * n * (n - 1) * m + 2 * m * (m - 1) * n + actual_1 = nx.schultz_index(cbg) + + expected_2 = n * m * (n * m) + n * (n - 1) * m * m + m * (m - 1) * n * n + actual_2 = nx.gutman_index(cbg) + + assert expected_1 == actual_1 + assert expected_2 == actual_2 + + +def test_schultz_and_gutman_index_of_complete_bipartite_graph_2(): + n = 2 + m = 5 + cbg = nx.complete_bipartite_graph(n, m) + + expected_1 = n * m * (n + m) + 2 * n * (n - 1) * m + 2 * m * (m - 1) * n + actual_1 = nx.schultz_index(cbg) + + expected_2 = n * m * (n * m) + n * (n - 1) * m * m + m * (m - 1) * n * n + actual_2 = nx.gutman_index(cbg) + + assert expected_1 == actual_1 + assert expected_2 == actual_2 + + +def test_schultz_and_gutman_index_of_complete_graph(): + n = 5 + cg = nx.complete_graph(n) + + expected_1 = n * (n - 1) * (n - 1) + actual_1 = nx.schultz_index(cg) + + assert expected_1 == actual_1 + + expected_2 = n * (n - 1) * (n - 1) * (n - 1) / 2 + actual_2 = nx.gutman_index(cg) + + assert expected_2 == actual_2 + + +def test_schultz_and_gutman_index_of_odd_cycle_graph(): + k = 5 + n = 2 * k + 1 + ocg = nx.cycle_graph(n) + + expected_1 = 2 * n * k * (k + 1) + actual_1 = nx.schultz_index(ocg) + + expected_2 = 2 * n * k * (k + 1) + actual_2 = nx.gutman_index(ocg) + + assert expected_1 == actual_1 + assert expected_2 == actual_2 |