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- import networkx as nx
- def test_unionfind():
- # Fixed by: 2cddd5958689bdecdcd89b91ac9aaf6ce0e4f6b8
- # Previously (in 2.x), the UnionFind class could handle mixed types.
- # But in Python 3.x, this causes a TypeError such as:
- # TypeError: unorderable types: str() > int()
- #
- # Now we just make sure that no exception is raised.
- x = nx.utils.UnionFind()
- x.union(0, "a")
- def test_subtree_union():
- # See https://github.com/networkx/networkx/pull/3224
- # (35db1b551ee65780794a357794f521d8768d5049).
- # Test if subtree unions hare handled correctly by to_sets().
- uf = nx.utils.UnionFind()
- uf.union(1, 2)
- uf.union(3, 4)
- uf.union(4, 5)
- uf.union(1, 5)
- assert list(uf.to_sets()) == [{1, 2, 3, 4, 5}]
- def test_unionfind_weights():
- # Tests if weights are computed correctly with unions of many elements
- uf = nx.utils.UnionFind()
- uf.union(1, 4, 7)
- uf.union(2, 5, 8)
- uf.union(3, 6, 9)
- uf.union(1, 2, 3, 4, 5, 6, 7, 8, 9)
- assert uf.weights[uf[1]] == 9
- def test_unbalanced_merge_weights():
- # Tests if the largest set's root is used as the new root when merging
- uf = nx.utils.UnionFind()
- uf.union(1, 2, 3)
- uf.union(4, 5, 6, 7, 8, 9)
- assert uf.weights[uf[1]] == 3
- assert uf.weights[uf[4]] == 6
- largest_root = uf[4]
- uf.union(1, 4)
- assert uf[1] == largest_root
- assert uf.weights[largest_root] == 9
- def test_empty_union():
- # Tests if a null-union does nothing.
- uf = nx.utils.UnionFind((0, 1))
- uf.union()
- assert uf[0] == 0
- assert uf[1] == 1
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