def test_adding_duplicate_edges_to_a_weight_graph_adds_unique_edges(num):
"""Test that adding duplicate edges to the graph unique edges."""
from weight_graph import Graph
g = Graph()
for x in range(num):
g.add_edge(x % 5, x % 5 + 1, x + 1)
assert len(g.edges()) == 5 if num > 5 else num
def test_edges_of_filled_weight_graph_has_all_edges(num):
"""Test that edges lists all the edges in a graph."""
from weight_graph import Graph
g = Graph()
for x in range(num):
g.add_edge(x, x + 1, x + 2)
assert len(g.edges()) == num
def test_adding_unique_edges_to_a_weight_graph_adds_all_edges(num):
"""Test that adding unique edges to the weight graph adds all edges."""
from weight_graph import Graph
g = Graph()
for x in range(num):
g.add_edge(x, x + 1, x + 2)
assert len(g.edges()) == num
def test_adjacent_returns_false_if_specific_pair_of_values_has_no_edge(num):
"""Test adjacent is false if pair of values given doesn't exist in graph as edge."""
from weight_graph import Graph
g = Graph()
for x in range(num):
g.add_edge(x, x + 1, x % 3 + 1)
for x in range(num - 1):
assert not g.adjacent(x, x + 2)
def test_adjacent_returns_true_if_specific_pair_of_values_given_exist(num):
"""Test adjacent is true if pair of values given exist in graph as edge."""
from weight_graph import Graph
g = Graph()
for x in range(num):
g.add_edge(x, x + 1, x % 3 + 1)
for x in range(num):
assert g.adjacent(x, x + 1)
def test_del_edge(node, result):
"""Test to check the deleted edges aren't there."""
from weight_graph import Graph
g = Graph()
for idx in node:
g.add_node(idx)
g.add_edge(2, 3)
g.add_edge(1, 4)
assert g.del_edge(1, 4) == result
def test_edge(node, result):
"""Test to check if all edges are there."""
from weight_graph import Graph
g = Graph()
for idx in node:
g.add_node(idx)
g.add_edge(2, 3)
g.add_edge(1, 4)
assert g.edges() == result
def test_neighbor(node, n, result):
"""Test to check that the correct node have the right edge."""
from weight_graph import Graph
g = Graph()
for idx in node:
g.add_node(idx)
g.add_edge(1, 1)
g.add_edge(1, 4)
g.add_edge(4, 2)
g.add_edge(3, 5)
assert g.neighbors(n) == result
def complex_weight_graph():
"""Create a graph with interconnecting nodes and edges."""
from weight_graph import Graph
g = Graph()
g.add_edge(0, 1, 4)
g.add_edge(1, 0, 4)
g.add_edge(0, 7, 8)
g.add_edge(7, 0, 8)
g.add_edge(1, 7, 11)
g.add_edge(7, 1, 11)
g.add_edge(7, 8, 7)
g.add_edge(8, 7, 7)
g.add_edge(7, 6, 1)
g.add_edge(6, 7, 1)
g.add_edge(1, 2, 8)
g.add_edge(2, 1, 8)
g.add_edge(2, 5, 4)
g.add_edge(5, 2, 4)
g.add_edge(2, 8, 2)
g.add_edge(8, 2, 2)
g.add_edge(2, 3, 7)
g.add_edge(3, 2, 7)
g.add_edge(8, 6, 6)
g.add_edge(6, 8, 6)
g.add_edge(6, 5, 2)
g.add_edge(5, 6, 2)
g.add_edge(5, 3, 14)
g.add_edge(3, 5, 14)
g.add_edge(5, 4, 10)
g.add_edge(4, 5, 10)
g.add_edge(3, 4, 9)
g.add_edge(4, 3, 9)
return g
from heapq import heappop, heappush
def dijkstra(graph, start, target):
unique = count()
visited = set()
heap = [(0, unique, start, ())]
while heap:
weight, junk, node, path = heappop(heap)
if node == target:
return weight, path
if node not in visited:
visited.add(node)
for neighbor, edge in graph[node].items():
heappush(heap, (weight + edge, next(unique),
neighbor, (neighbor, path)))
if __name__ == '__main__':
g = Graph()
g.add_node('A')
g.add_node('B')
g.add_node('C')
g.add_node('D')
g.add_edge('A', 'B', 4)
g.add_edge('A', 'C', 20)
g.add_edge('B', 'D', 5)
g.add_edge('C', 'D', 200)
dijkstra(g, 'A', 'D')
