def add_edge(self, from_vertex, to_vertex, weight=0):
"""Add an edge between two vertices.
Args:
from_vertex: start vertex id
to_vertex: end vertex id
weight (int): weight of edge
Raises:
DataStructureIsEmptyException: if graph is empty
NotContainsElementException: if vertex not contains in graph
"""
if self.is_empty:
raise DataStructureIsEmptyException(data_structure_is_empty_message())
if from_vertex not in self._vertices:
raise NotContainsElementException(not_contains_vertex_message(from_vertex))
if to_vertex not in self._vertices:
raise NotContainsElementException(not_contains_vertex_message(to_vertex))
first_vertex = self._vertices[from_vertex]
second_vertex = self._vertices[to_vertex]
first_vertex.add_adjacent_vertex(second_vertex, weight)
edge = Edge(first_vertex, second_vertex, weight)
self._edges.append(edge)
def test_vertex_not_found2():
graph = Graph()
graph.create_vertex_by_id('B')
with pytest.raises(NotContainsElementException) as exception_info:
graph.add_edge('A', 'B')
assert str(exception_info.value) == not_contains_vertex_message('A')
def test_dijkstra_negative2(f):
graph = Graph()
graph.create_vertex_by_id('A')
with pytest.raises(NotContainsElementException) as exception_info:
f(graph, Vertex('B'))
assert str(exception_info.value) == not_contains_vertex_message('B')
def test_get_vertex_by_id_negative1():
graph = Graph()
graph.create_vertex_by_id('B')
with pytest.raises(NotContainsElementException) as exception_info:
vertex = graph.get_vertex_by_id('A')
assert str(exception_info.value) == not_contains_vertex_message('A')
def test_edge_weight_to_negative():
vertex_s = Vertex('S')
vertex_a = Vertex('A')
vertex_b = Vertex('B')
vertex_s.add_adjacent_vertex(vertex_a)
with pytest.raises(NotContainsElementException) as exception_info:
weight = vertex_s.edge_weight_to(vertex_b)
assert str(exception_info.value) == not_contains_vertex_message('B')
def edge_weight_to(self, vertex):
"""Return edge weight to vertex.
Args:
vertex: edge from self to vertex
Raises:
NotContainsElementException: if vertex not contains in adjacency list
Returns:
weight (int) edge weight from self to vertex
"""
if vertex not in self:
raise NotContainsElementException(
not_contains_vertex_message(vertex.identifier))
return self._adjacency_list[vertex]
def get_vertex_by_id(self, vertex_id):
"""Return (not extract) vertex from graph.
Args:
vertex_id: vertex for return
Returns:
vertex: vertex by id
Raises:
DataStructureIsEmptyException: if graph is empty
NotContainsElementException: if graph not contains vertex
"""
if self.is_empty:
raise DataStructureIsEmptyException(data_structure_is_empty_message())
if vertex_id not in self._vertices:
raise NotContainsElementException(not_contains_vertex_message(vertex_id))
return self._vertices[vertex_id]
def bellman_ford(graph, start_vertex):
"""Return the distance from the starting vertex to the rest.
Args:
graph: graph for search
start_vertex: start vertex for search
Raises:
DataStructureIsEmptyException: if graph is empty
NotContainsElementException: if graph not contains start vertex
Returns:
distances: collection storing the distance from the starting vertex to the rest
"""
if graph.is_empty:
raise DataStructureIsEmptyException(data_structure_is_empty_message())
if start_vertex.identifier not in graph:
raise NotContainsElementException(
not_contains_vertex_message(start_vertex.identifier))
return _bellman_ford(graph, start_vertex)