### diff env/lib/python3.9/site-packages/networkx/algorithms/approximation/tests/test_connectivity.py @ 0:4f3585e2f14bdraftdefaulttip

author shellac Mon, 22 Mar 2021 18:12:50 +0000
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```--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.9/site-packages/networkx/algorithms/approximation/tests/test_connectivity.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,199 @@
+import pytest
+
+import networkx as nx
+from networkx.algorithms import approximation as approx
+
+
+def test_global_node_connectivity():
+    # Figure 1 chapter on Connectivity
+    G = nx.Graph()
+        [
+            (1, 2),
+            (1, 3),
+            (1, 4),
+            (1, 5),
+            (2, 3),
+            (2, 6),
+            (3, 4),
+            (3, 6),
+            (4, 6),
+            (4, 7),
+            (5, 7),
+            (6, 8),
+            (6, 9),
+            (7, 8),
+            (7, 10),
+            (8, 11),
+            (9, 10),
+            (9, 11),
+            (10, 11),
+        ]
+    )
+    assert 2 == approx.local_node_connectivity(G, 1, 11)
+    assert 2 == approx.node_connectivity(G)
+    assert 2 == approx.node_connectivity(G, 1, 11)
+
+
+def test_white_harary1():
+    # Figure 1b white and harary (2001)
+    # A graph with high adhesion (edge connectivity) and low cohesion
+    # (node connectivity)
+    G = nx.disjoint_union(nx.complete_graph(4), nx.complete_graph(4))
+    G.remove_node(7)
+    for i in range(4, 7):
+    G = nx.disjoint_union(G, nx.complete_graph(4))
+    G.remove_node(G.order() - 1)
+    for i in range(7, 10):
+    assert 1 == approx.node_connectivity(G)
+
+
+def test_complete_graphs():
+    for n in range(5, 25, 5):
+        G = nx.complete_graph(n)
+        assert n - 1 == approx.node_connectivity(G)
+        assert n - 1 == approx.node_connectivity(G, 0, 3)
+
+
+def test_empty_graphs():
+    for k in range(5, 25, 5):
+        G = nx.empty_graph(k)
+        assert 0 == approx.node_connectivity(G)
+        assert 0 == approx.node_connectivity(G, 0, 3)
+
+
+def test_petersen():
+    G = nx.petersen_graph()
+    assert 3 == approx.node_connectivity(G)
+    assert 3 == approx.node_connectivity(G, 0, 5)
+
+
+# Approximation fails with tutte graph
+# def test_tutte():
+#    G = nx.tutte_graph()
+#    assert_equal(3, approx.node_connectivity(G))
+
+
+def test_dodecahedral():
+    G = nx.dodecahedral_graph()
+    assert 3 == approx.node_connectivity(G)
+    assert 3 == approx.node_connectivity(G, 0, 5)
+
+
+def test_octahedral():
+    G = nx.octahedral_graph()
+    assert 4 == approx.node_connectivity(G)
+    assert 4 == approx.node_connectivity(G, 0, 5)
+
+
+# Approximation can fail with icosahedral graph depending
+# on iteration order.
+# def test_icosahedral():
+#    G=nx.icosahedral_graph()
+#    assert_equal(5, approx.node_connectivity(G))
+#    assert_equal(5, approx.node_connectivity(G, 0, 5))
+
+
+def test_only_source():
+    G = nx.complete_graph(5)
+    pytest.raises(nx.NetworkXError, approx.node_connectivity, G, s=0)
+
+
+def test_only_target():
+    G = nx.complete_graph(5)
+    pytest.raises(nx.NetworkXError, approx.node_connectivity, G, t=0)
+
+
+def test_missing_source():
+    G = nx.path_graph(4)
+    pytest.raises(nx.NetworkXError, approx.node_connectivity, G, 10, 1)
+
+
+def test_missing_target():
+    G = nx.path_graph(4)
+    pytest.raises(nx.NetworkXError, approx.node_connectivity, G, 1, 10)
+
+
+def test_source_equals_target():
+    G = nx.complete_graph(5)
+    pytest.raises(nx.NetworkXError, approx.local_node_connectivity, G, 0, 0)
+
+
+def test_directed_node_connectivity():
+    G = nx.cycle_graph(10, create_using=nx.DiGraph())  # only one direction
+    D = nx.cycle_graph(10).to_directed()  # 2 reciprocal edges
+    assert 1 == approx.node_connectivity(G)
+    assert 1 == approx.node_connectivity(G, 1, 4)
+    assert 2 == approx.node_connectivity(D)
+    assert 2 == approx.node_connectivity(D, 1, 4)
+
+
+class TestAllPairsNodeConnectivityApprox:
+    @classmethod
+    def setup_class(cls):
+        cls.path = nx.path_graph(7)
+        cls.directed_path = nx.path_graph(7, create_using=nx.DiGraph())
+        cls.cycle = nx.cycle_graph(7)
+        cls.directed_cycle = nx.cycle_graph(7, create_using=nx.DiGraph())
+        cls.gnp = nx.gnp_random_graph(30, 0.1)
+        cls.directed_gnp = nx.gnp_random_graph(30, 0.1, directed=True)
+        cls.K20 = nx.complete_graph(20)
+        cls.K10 = nx.complete_graph(10)
+        cls.K5 = nx.complete_graph(5)
+        cls.G_list = [
+            cls.path,
+            cls.directed_path,
+            cls.cycle,
+            cls.directed_cycle,
+            cls.gnp,
+            cls.directed_gnp,
+            cls.K10,
+            cls.K5,
+            cls.K20,
+        ]
+
+    def test_cycles(self):
+        K_undir = approx.all_pairs_node_connectivity(self.cycle)
+        for source in K_undir:
+            for target, k in K_undir[source].items():
+                assert k == 2
+        K_dir = approx.all_pairs_node_connectivity(self.directed_cycle)
+        for source in K_dir:
+            for target, k in K_dir[source].items():
+                assert k == 1
+
+    def test_complete(self):
+        for G in [self.K10, self.K5, self.K20]:
+            K = approx.all_pairs_node_connectivity(G)
+            for source in K:
+                for target, k in K[source].items():
+                    assert k == len(G) - 1
+
+    def test_paths(self):
+        K_undir = approx.all_pairs_node_connectivity(self.path)
+        for source in K_undir:
+            for target, k in K_undir[source].items():
+                assert k == 1
+        K_dir = approx.all_pairs_node_connectivity(self.directed_path)
+        for source in K_dir:
+            for target, k in K_dir[source].items():
+                if source < target:
+                    assert k == 1
+                else:
+                    assert k == 0
+
+    def test_cutoff(self):
+        for G in [self.K10, self.K5, self.K20]:
+            for mp in [2, 3, 4]:
+                paths = approx.all_pairs_node_connectivity(G, cutoff=mp)
+                for source in paths:
+                    for target, K in paths[source].items():
+                        assert K == mp
+
+    def test_all_pairs_connectivity_nbunch(self):
+        G = nx.complete_graph(5)
+        nbunch = [0, 2, 3]
+        C = approx.all_pairs_node_connectivity(G, nbunch=nbunch)
+        assert len(C) == len(nbunch)```