### diff env/lib/python3.9/site-packages/networkx/algorithms/approximation/tests/test_kcomponents.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_kcomponents.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,300 @@
+# Test for approximation to k-components algorithm
+import pytest
+import networkx as nx
+from networkx.algorithms.approximation import k_components
+from networkx.algorithms.approximation.kcomponents import _AntiGraph, _same
+
+
+def build_k_number_dict(k_components):
+    k_num = {}
+    for k, comps in sorted(k_components.items()):
+        for comp in comps:
+            for node in comp:
+                k_num[node] = k
+    return k_num
+
+
+##
+# 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
+        # 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 + 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
+        # 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:
+        # 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
+        # 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:
+        nbrs2 = G[new_node + 9]
+        G.remove_node(new_node + 9)
+        for nbr in nbrs2:
+    return G
+
+
+# Helper function
+
+
+def _check_connectivity(G):
+    result = k_components(G)
+    for k, components in result.items():
+        if k < 3:
+            continue
+        for component in components:
+            C = G.subgraph(component)
+            K = nx.node_connectivity(C)
+            assert K >= k
+
+
+def test_torrents_and_ferraro_graph():
+    G = torrents_and_ferraro_graph()
+    _check_connectivity(G)
+
+
+def test_example_1():
+    G = graph_example_1()
+    _check_connectivity(G)
+
+
+def test_karate_0():
+    G = nx.karate_club_graph()
+    _check_connectivity(G)
+
+
+def test_karate_1():
+    karate_k_num = {
+        0: 4,
+        1: 4,
+        2: 4,
+        3: 4,
+        4: 3,
+        5: 3,
+        6: 3,
+        7: 4,
+        8: 4,
+        9: 2,
+        10: 3,
+        11: 1,
+        12: 2,
+        13: 4,
+        14: 2,
+        15: 2,
+        16: 2,
+        17: 2,
+        18: 2,
+        19: 3,
+        20: 2,
+        21: 2,
+        22: 2,
+        23: 3,
+        24: 3,
+        25: 3,
+        26: 2,
+        27: 3,
+        28: 3,
+        29: 3,
+        30: 4,
+        31: 3,
+        32: 4,
+        33: 4,
+    }
+    approx_karate_k_num = karate_k_num.copy()
+    approx_karate_k_num = 2
+    approx_karate_k_num = 2
+    G = nx.karate_club_graph()
+    k_comps = k_components(G)
+    k_num = build_k_number_dict(k_comps)
+    assert k_num in (karate_k_num, approx_karate_k_num)
+
+
+def test_example_1_detail_3_and_4():
+    G = graph_example_1()
+    result = k_components(G)
+    # In this example graph there are 8 3-components, 4 with 15 nodes
+    # and 4 with 5 nodes.
+    assert len(result) == 8
+    assert len([c for c in result if len(c) == 15]) == 4
+    assert len([c for c in result if len(c) == 5]) == 4
+    # There are also 8 4-components all with 5 nodes.
+    assert len(result) == 8
+    assert all(len(c) == 5 for c in result)
+    # Finally check that the k-components detected have actually node
+    # connectivity >= k.
+    for k, components in result.items():
+        if k < 3:
+            continue
+        for component in components:
+            K = nx.node_connectivity(G.subgraph(component))
+            assert K >= k
+
+
+def test_directed():
+    with pytest.raises(nx.NetworkXNotImplemented):
+        G = nx.gnp_random_graph(10, 0.4, directed=True)
+        kc = k_components(G)
+
+
+def test_same():
+    equal = {"A": 2, "B": 2, "C": 2}
+    slightly_different = {"A": 2, "B": 1, "C": 2}
+    different = {"A": 2, "B": 8, "C": 18}
+    assert _same(equal)
+    assert not _same(slightly_different)
+    assert _same(slightly_different, tol=1)
+    assert not _same(different)
+    assert not _same(different, tol=4)
+
+
+class TestAntiGraph:
+    @classmethod
+    def setup_class(cls):
+        cls.Gnp = nx.gnp_random_graph(20, 0.8)
+        cls.Anp = _AntiGraph(nx.complement(cls.Gnp))
+        cls.Gd = nx.davis_southern_women_graph()
+        cls.Gk = nx.karate_club_graph()
+        cls.Ak = _AntiGraph(nx.complement(cls.Gk))
+        cls.GA = [(cls.Gnp, cls.Anp), (cls.Gd, cls.Ad), (cls.Gk, cls.Ak)]
+
+    def test_size(self):
+        for G, A in self.GA:
+            n = G.order()
+            s = len(list(G.edges())) + len(list(A.edges()))
+            assert s == (n * (n - 1)) / 2
+
+    def test_degree(self):
+        for G, A in self.GA:
+            assert sorted(G.degree()) == sorted(A.degree())
+
+    def test_core_number(self):
+        for G, A in self.GA:
+            assert nx.core_number(G) == nx.core_number(A)
+
+    def test_connected_components(self):
+        for G, A in self.GA:
+            gc = [set(c) for c in nx.connected_components(G)]
+            ac = [set(c) for c in nx.connected_components(A)]
+            for comp in ac:
+                assert comp in gc
+
+        for G, A in self.GA:
+            for n, nbrs in G.adj.items():
+
+        for G, A in self.GA:
+            for n, nbrs in G.adjacency():
+                assert (n, set(nbrs)) in a_adj
+
+    def test_neighbors(self):
+        for G, A in self.GA:
+            node = list(G.nodes())
+            assert set(G.neighbors(node)) == set(A.neighbors(node))
+
+    def test_node_not_in_graph(self):
+        for G, A in self.GA:
+            node = "non_existent_node"
+            pytest.raises(nx.NetworkXError, A.neighbors, node)
+            pytest.raises(nx.NetworkXError, G.neighbors, node)
+
+    def test_degree_thingraph(self):
+        for G, A in self.GA:
+            node = list(G.nodes())
+            nodes = list(G.nodes())[1:4]
+            assert G.degree(node) == A.degree(node)
+            assert sum(d for n, d in G.degree()) == sum(d for n, d in A.degree())
+            # AntiGraph is a ThinGraph, so all the weights are 1
+            assert sum(d for n, d in A.degree()) == sum(
+                d for n, d in A.degree(weight="weight")
+            )
+            assert sum(d for n, d in G.degree(nodes)) == sum(
+                d for n, d in A.degree(nodes)
+            )```