def unite(self, vertex_x, vertex_y):
"""Combine the sets containing.
Args:
vertex_x: element first set
vertex_y: element second set
Raises:
NotContainsElementException: if dsu not contains vertex
DataStructureIsEmptyException: if dsu is empty
"""
if self.size == 0:
raise DataStructureIsEmptyException(data_structure_is_empty_message())
if vertex_x not in self._set:
raise NotContainsElementException(not_contains_element_message())
if vertex_y not in self._set:
raise NotContainsElementException(not_contains_element_message())
parent_x = self.find(vertex_x)
parent_y = self.find(vertex_y)
if secrets.randbelow(10) % 2 == 0:
self._set[parent_x] = parent_y
else:
self._set[parent_y] = parent_x
def test_dijkstra_negative1(f):
graph = Graph()
with pytest.raises(DataStructureIsEmptyException) as exception_info:
f(graph, Vertex('A'))
assert str(exception_info.value) == data_structure_is_empty_message()
def test_get_vertex_by_id_negative2():
graph = Graph()
with pytest.raises(DataStructureIsEmptyException) as exception_info:
vertex = graph.get_vertex_by_id('A')
assert str(exception_info.value) == data_structure_is_empty_message()
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 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)
def find(self, vertex):
"""Return unique id of set.
Args:
vertex: element for search id
Raises:
NotContainsElementException: if dsu not contains vertex
DataStructureIsEmptyException: if dsu is empty
Returns:
id: unique set identifier found by arg
"""
if self.size == 0:
raise DataStructureIsEmptyException(data_structure_is_empty_message())
if vertex not in self._set:
raise NotContainsElementException(not_contains_element_message())
if self._set[vertex] == vertex:
return vertex
self._set[vertex] = self.find(self._set[vertex])
return self._set[vertex]
def test_add_edge_in_empty_graph():
graph = Graph()
with pytest.raises(DataStructureIsEmptyException) as exception_info:
graph.add_edge('A', 'B')
assert str(exception_info.value) == data_structure_is_empty_message()
