diff env/lib/python3.9/site-packages/networkx/algorithms/connectivity/tests/test_stoer_wagner.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_stoer_wagner.py	Mon Mar 22 18:12:50 2021 +0000
@@ -0,0 +1,100 @@
+from itertools import chain
+import networkx as nx
+import pytest
+
+
+def _check_partition(G, cut_value, partition, weight):
+    assert isinstance(partition, tuple)
+    assert len(partition) == 2
+    assert isinstance(partition[0], list)
+    assert isinstance(partition[1], list)
+    assert len(partition[0]) > 0
+    assert len(partition[1]) > 0
+    assert sum(map(len, partition)) == len(G)
+    assert set(chain.from_iterable(partition)) == set(G)
+    partition = tuple(map(set, partition))
+    w = 0
+    for u, v, e in G.edges(data=True):
+        if (u in partition[0]) == (v in partition[1]):
+            w += e.get(weight, 1)
+    assert w == cut_value
+
+
+def _test_stoer_wagner(G, answer, weight="weight"):
+    cut_value, partition = nx.stoer_wagner(G, weight, heap=nx.utils.PairingHeap)
+    assert cut_value == answer
+    _check_partition(G, cut_value, partition, weight)
+    cut_value, partition = nx.stoer_wagner(G, weight, heap=nx.utils.BinaryHeap)
+    assert cut_value == answer
+    _check_partition(G, cut_value, partition, weight)
+
+
+def test_graph1():
+    G = nx.Graph()
+    G.add_edge("x", "a", weight=3)
+    G.add_edge("x", "b", weight=1)
+    G.add_edge("a", "c", weight=3)
+    G.add_edge("b", "c", weight=5)
+    G.add_edge("b", "d", weight=4)
+    G.add_edge("d", "e", weight=2)
+    G.add_edge("c", "y", weight=2)
+    G.add_edge("e", "y", weight=3)
+    _test_stoer_wagner(G, 4)
+
+
+def test_graph2():
+    G = nx.Graph()
+    G.add_edge("x", "a")
+    G.add_edge("x", "b")
+    G.add_edge("a", "c")
+    G.add_edge("b", "c")
+    G.add_edge("b", "d")
+    G.add_edge("d", "e")
+    G.add_edge("c", "y")
+    G.add_edge("e", "y")
+    _test_stoer_wagner(G, 2)
+
+
+def test_graph3():
+    # Source:
+    # Stoer, M. and Wagner, F. (1997). "A simple min-cut algorithm". Journal of
+    # the ACM 44 (4), 585-591.
+    G = nx.Graph()
+    G.add_edge(1, 2, weight=2)
+    G.add_edge(1, 5, weight=3)
+    G.add_edge(2, 3, weight=3)
+    G.add_edge(2, 5, weight=2)
+    G.add_edge(2, 6, weight=2)
+    G.add_edge(3, 4, weight=4)
+    G.add_edge(3, 7, weight=2)
+    G.add_edge(4, 7, weight=2)
+    G.add_edge(4, 8, weight=2)
+    G.add_edge(5, 6, weight=3)
+    G.add_edge(6, 7, weight=1)
+    G.add_edge(7, 8, weight=3)
+    _test_stoer_wagner(G, 4)
+
+
+def test_weight_name():
+    G = nx.Graph()
+    G.add_edge(1, 2, weight=1, cost=8)
+    G.add_edge(1, 3, cost=2)
+    G.add_edge(2, 3, cost=4)
+    _test_stoer_wagner(G, 6, weight="cost")
+
+
+def test_exceptions():
+    G = nx.Graph()
+    pytest.raises(nx.NetworkXError, nx.stoer_wagner, G)
+    G.add_node(1)
+    pytest.raises(nx.NetworkXError, nx.stoer_wagner, G)
+    G.add_node(2)
+    pytest.raises(nx.NetworkXError, nx.stoer_wagner, G)
+    G.add_edge(1, 2, weight=-2)
+    pytest.raises(nx.NetworkXError, nx.stoer_wagner, G)
+    G = nx.DiGraph()
+    pytest.raises(nx.NetworkXNotImplemented, nx.stoer_wagner, G)
+    G = nx.MultiGraph()
+    pytest.raises(nx.NetworkXNotImplemented, nx.stoer_wagner, G)
+    G = nx.MultiDiGraph()
+    pytest.raises(nx.NetworkXNotImplemented, nx.stoer_wagner, G)