diff env/lib/python3.9/site-packages/networkx/algorithms/connectivity/tests/test_kcutsets.py @ 0:4f3585e2f14b draft default tip

"planemo upload commit 60cee0fc7c0cda8592644e1aad72851dec82c959"

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/networkx/algorithms/connectivity/tests/test_kcutsets.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,266 @@
+# Jordi Torrents
+# Test for k-cutsets
+import itertools
+import pytest
+
+import networkx as nx
+from networkx.algorithms import flow
+from networkx.algorithms.connectivity.kcutsets import _is_separating_set
+
+MAX_CUTSETS_TO_TEST = 4  # originally 100. cut to decrease testing time
+
+flow_funcs = [
+    flow.boykov_kolmogorov,
+    flow.dinitz,
+    flow.edmonds_karp,
+    flow.preflow_push,
+    flow.shortest_augmenting_path,
+]
+
+
+##
+# Some nice synthetic graphs
+##
+def graph_example_1():
+    G = nx.convert_node_labels_to_integers(
+        nx.grid_graph([5, 5]), label_attribute="labels"
+    )
+    rlabels = nx.get_node_attributes(G, "labels")
+    labels = {v: k for k, v in rlabels.items()}
+
+    for nodes in [
+        (labels[(0, 0)], labels[(1, 0)]),
+        (labels[(0, 4)], labels[(1, 4)]),
+        (labels[(3, 0)], labels[(4, 0)]),
+        (labels[(3, 4)], labels[(4, 4)]),
+    ]:
+        new_node = G.order() + 1
+        # Petersen graph is triconnected
+        P = nx.petersen_graph()
+        G = nx.disjoint_union(G, P)
+        # Add two edges between the grid and P
+        G.add_edge(new_node + 1, nodes[0])
+        G.add_edge(new_node, nodes[1])
+        # K5 is 4-connected
+        K = nx.complete_graph(5)
+        G = nx.disjoint_union(G, K)
+        # Add three edges between P and K5
+        G.add_edge(new_node + 2, new_node + 11)
+        G.add_edge(new_node + 3, new_node + 12)
+        G.add_edge(new_node + 4, new_node + 13)
+        # Add another K5 sharing a node
+        G = nx.disjoint_union(G, K)
+        nbrs = G[new_node + 10]
+        G.remove_node(new_node + 10)
+        for nbr in nbrs:
+            G.add_edge(new_node + 17, nbr)
+        G.add_edge(new_node + 16, new_node + 5)
+    return G
+
+
+def torrents_and_ferraro_graph():
+    G = nx.convert_node_labels_to_integers(
+        nx.grid_graph([5, 5]), label_attribute="labels"
+    )
+    rlabels = nx.get_node_attributes(G, "labels")
+    labels = {v: k for k, v in rlabels.items()}
+
+    for nodes in [(labels[(0, 4)], labels[(1, 4)]), (labels[(3, 4)], labels[(4, 4)])]:
+        new_node = G.order() + 1
+        # Petersen graph is triconnected
+        P = nx.petersen_graph()
+        G = nx.disjoint_union(G, P)
+        # Add two edges between the grid and P
+        G.add_edge(new_node + 1, nodes[0])
+        G.add_edge(new_node, nodes[1])
+        # K5 is 4-connected
+        K = nx.complete_graph(5)
+        G = nx.disjoint_union(G, K)
+        # Add three edges between P and K5
+        G.add_edge(new_node + 2, new_node + 11)
+        G.add_edge(new_node + 3, new_node + 12)
+        G.add_edge(new_node + 4, new_node + 13)
+        # Add another K5 sharing a node
+        G = nx.disjoint_union(G, K)
+        nbrs = G[new_node + 10]
+        G.remove_node(new_node + 10)
+        for nbr in nbrs:
+            G.add_edge(new_node + 17, nbr)
+        # Commenting this makes the graph not biconnected !!
+        # This stupid mistake make one reviewer very angry :P
+        G.add_edge(new_node + 16, new_node + 8)
+
+    for nodes in [(labels[(0, 0)], labels[(1, 0)]), (labels[(3, 0)], labels[(4, 0)])]:
+        new_node = G.order() + 1
+        # Petersen graph is triconnected
+        P = nx.petersen_graph()
+        G = nx.disjoint_union(G, P)
+        # Add two edges between the grid and P
+        G.add_edge(new_node + 1, nodes[0])
+        G.add_edge(new_node, nodes[1])
+        # K5 is 4-connected
+        K = nx.complete_graph(5)
+        G = nx.disjoint_union(G, K)
+        # Add three edges between P and K5
+        G.add_edge(new_node + 2, new_node + 11)
+        G.add_edge(new_node + 3, new_node + 12)
+        G.add_edge(new_node + 4, new_node + 13)
+        # Add another K5 sharing two nodes
+        G = nx.disjoint_union(G, K)
+        nbrs = G[new_node + 10]
+        G.remove_node(new_node + 10)
+        for nbr in nbrs:
+            G.add_edge(new_node + 17, nbr)
+        nbrs2 = G[new_node + 9]
+        G.remove_node(new_node + 9)
+        for nbr in nbrs2:
+            G.add_edge(new_node + 18, nbr)
+    return G
+
+
+# Helper function
+def _check_separating_sets(G):
+    for cc in nx.connected_components(G):
+        if len(cc) < 3:
+            continue
+        Gc = G.subgraph(cc)
+        node_conn = nx.node_connectivity(Gc)
+        all_cuts = nx.all_node_cuts(Gc)
+        # Only test a limited number of cut sets to reduce test time.
+        for cut in itertools.islice(all_cuts, MAX_CUTSETS_TO_TEST):
+            assert node_conn == len(cut)
+            assert not nx.is_connected(nx.restricted_view(G, cut, []))
+
+
[e-mail]
+def test_torrents_and_ferraro_graph():
+    G = torrents_and_ferraro_graph()
+    _check_separating_sets(G)
+
+
+def test_example_1():
+    G = graph_example_1()
+    _check_separating_sets(G)
+
+
+def test_random_gnp():
+    G = nx.gnp_random_graph(100, 0.1, seed=42)
+    _check_separating_sets(G)
+
+
+def test_shell():
+    constructor = [(20, 80, 0.8), (80, 180, 0.6)]
+    G = nx.random_shell_graph(constructor, seed=42)
+    _check_separating_sets(G)
+
+
+def test_configuration():
+    deg_seq = nx.random_powerlaw_tree_sequence(100, tries=5, seed=72)
+    G = nx.Graph(nx.configuration_model(deg_seq))
+    G.remove_edges_from(nx.selfloop_edges(G))
+    _check_separating_sets(G)
+
+
+def test_karate():
+    G = nx.karate_club_graph()
+    _check_separating_sets(G)
+
+
+def _generate_no_biconnected(max_attempts=50):
+    attempts = 0
+    while True:
+        G = nx.fast_gnp_random_graph(100, 0.0575, seed=42)
+        if nx.is_connected(G) and not nx.is_biconnected(G):
+            attempts = 0
+            yield G
+        else:
+            if attempts >= max_attempts:
+                msg = f"Tried {attempts} times: no suitable Graph."
+                raise Exception(msg)
+            else:
+                attempts += 1
+
+
+def test_articulation_points():
+    Ggen = _generate_no_biconnected()
+    for i in range(1):  # change 1 to 3 or more for more realizations.
+        G = next(Ggen)
+        articulation_points = list({a} for a in nx.articulation_points(G))
+        for cut in nx.all_node_cuts(G):
+            assert cut in articulation_points
+
+
+def test_grid_2d_graph():
+    # All minimum node cuts of a 2d grid
+    # are the four pairs of nodes that are
+    # neighbors of the four corner nodes.
+    G = nx.grid_2d_graph(5, 5)
+    solution = [{(0, 1), (1, 0)}, {(3, 0), (4, 1)}, {(3, 4), (4, 3)}, {(0, 3), (1, 4)}]
+    for cut in nx.all_node_cuts(G):
+        assert cut in solution
+
+
+def test_disconnected_graph():
+    G = nx.fast_gnp_random_graph(100, 0.01, seed=42)
+    cuts = nx.all_node_cuts(G)
+    pytest.raises(nx.NetworkXError, next, cuts)
+
+
[e-mail]
+def test_alternative_flow_functions():
+    graphs = [nx.grid_2d_graph(4, 4), nx.cycle_graph(5)]
+    for G in graphs:
+        node_conn = nx.node_connectivity(G)
+        for flow_func in flow_funcs:
+            all_cuts = nx.all_node_cuts(G, flow_func=flow_func)
+            # Only test a limited number of cut sets to reduce test time.
+            for cut in itertools.islice(all_cuts, MAX_CUTSETS_TO_TEST):
+                assert node_conn == len(cut)
+                assert not nx.is_connected(nx.restricted_view(G, cut, []))
+
+
+def test_is_separating_set_complete_graph():
+    G = nx.complete_graph(5)
+    assert _is_separating_set(G, {0, 1, 2, 3})
+
+
+def test_is_separating_set():
+    for i in [5, 10, 15]:
+        G = nx.star_graph(i)
+        max_degree_node = max(G, key=G.degree)
+        assert _is_separating_set(G, {max_degree_node})
+
+
+def test_non_repeated_cuts():
+    # The algorithm was repeating the cut {0, 1} for the giant biconnected
+    # component of the Karate club graph.
+    K = nx.karate_club_graph()
+    bcc = max(list(nx.biconnected_components(K)), key=len)
+    G = K.subgraph(bcc)
+    solution = [{32, 33}, {2, 33}, {0, 3}, {0, 1}, {29, 33}]
+    cuts = list(nx.all_node_cuts(G))
+    if len(solution) != len(cuts):
+        print(nx.info(G))
+        print(f"Solution: {solution}")
+        print(f"Result: {cuts}")
+    assert len(solution) == len(cuts)
+    for cut in cuts:
+        assert cut in solution
+
+
+def test_cycle_graph():
+    G = nx.cycle_graph(5)
+    solution = [{0, 2}, {0, 3}, {1, 3}, {1, 4}, {2, 4}]
+    cuts = list(nx.all_node_cuts(G))
+    assert len(solution) == len(cuts)
+    for cut in cuts:
+        assert cut in solution
+
+
+def test_complete_graph():
+    G = nx.complete_graph(5)
+    solution = [{0, 1, 2, 3}, {0, 1, 2, 4}, {0, 1, 3, 4}, {0, 2, 3, 4}, {1, 2, 3, 4}]
+    cuts = list(nx.all_node_cuts(G))
+    assert len(solution) == len(cuts)
+    for cut in cuts:
+        assert cut in solution