class TestGraph(unittest.TestCase):
def setUp(self):
# A brand new graph.
self.new = Graph()
# A disconnected graph
self.disconnected = Graph()
self.disconnected.add_edge(1, 2)
self.disconnected.add_edge(3, 4)
# A complete graph
self.complete = Graph()
self.complete.add_edge(1, 2, 3)
self.complete.add_edge(2, 3, 5)
self.complete.add_edge(3, 4, 7)
self.complete.add_edge(4, 1, 5)
self.complete.add_edge(1, 3, 4)
self.complete.add_edge(2, 4, 6)
def test_has_edge(self):
self.assertFalse(self.new.has_edge(1, 2))
self.assertFalse(self.disconnected.has_edge(2, 3))
self.assertFalse(self.disconnected.has_edge(1, 1))
self.assertFalse(self.disconnected.has_edge(5, 1))
self.assertTrue(self.disconnected.has_edge(2, 1))
def test_unweighted_edges(self):
self.assertEqual(self.new.unweighted_edges(), set())
self.assertEqual(len(self.disconnected.unweighted_edges()), 2)
self.assertEqual(len(self.complete.unweighted_edges()), 6)
for graph in self.disconnected, self.complete:
edges = graph.unweighted_edges()
for (source, target) in edges:
self.assertNotIn((target, source), edges)
def test_weighted_edges(self):
self.assertEqual(self.new.weighted_edges(), set())
self.assertEqual(len(self.disconnected.weighted_edges()), 2)
self.assertEqual(len(self.complete.weighted_edges()), 6)
edges = self.disconnected.weighted_edges()
for (source, target, weight) in edges:
self.assertEqual(weight, 1)
self.assertNotIn((target, source, weight), edges)
edges = self.complete.weighted_edges()
for (source, target, weight) in edges:
self.assertEqual(weight, source + target)
self.assertNotIn((target, source, weight), edges)
def test_topological_sort(self):
for graph in self.new, self.disconnected, self.complete:
self.assertEqual(graph.topological_sort(), [])
def test_best_tour(self):
self.assertIn(self.complete.best_tour(),
[[1, 2, 3, 4, 1], [2, 3, 4, 1, 2], [3, 4, 1, 2, 3],
[4, 1, 2, 3, 4]])
def test_minimum_spanning_tree(self):
mst = self.complete.minimum_spanning_tree(4)
self.assertEqual(mst.nodes(), self.complete.nodes())
self.assertEqual(mst.unweighted_edges(), {(4, 1), (1, 2), (1, 3)})
cities.add_edge("Wick", "Wrexham", 508)
def print_graph(graph):
"""Print the number of nodes and edges, and each edge."""
nodes = graph.nodes()
edges = graph.weighted_edges()
print("A graph with", len(nodes), "nodes and", len(edges), "edges")
for (source, target, weight) in edges:
print("Edge from", source, "to", target, "with weight", weight)
# If this file is imported, do nothing.
# If it is run as a script, execute the app.
if __name__ == "__main__":
tour = cities.best_tour()
print(tour, "\nis a shortest tour of length", cities.weight(tour))
print()
print("A minimum spanning tree:")
print_graph(cities.minimum_spanning_tree("Luton"))
print()
print("Type two cities to get the shortest path between them.")
print("To end the program, just type ENTER.")
start = input("Start city: ")
while start:
end = input("End city: ")
if cities.has_node(start) and cities.has_node(end):
path = cities.shortest_path(start, end)
print(path, "is a shortest path of length", cities.weight(path))
else:
print("At least one of the cities doesn't exist.")
