class AnimalShelter():
def __init__(self):
self.cat_queue = Queue()
self.dog_queue = Queue()
self.animals_served = 0
def enqueue(self, incoming_animal):
type_of_animal = type(incoming_animal)
# https://docs.python.org/3/library/functions.html#type
self.animals_served += 1
incoming_animal.animal_id = self.animals_served
if type_of_animal == Cat:
self.cat_queue.enqueue(incoming_animal)
elif type_of_animal == Dog:
self.dog_queue.enqueue(incoming_animal)
else:
raise InvalidOperationError("Sorry, we don't accept that type of animal here.")
def dequeue(self, request_type = None):
if request_type == "cat":
return self.cat_queue.dequeue()
elif request_type == "dog":
return self.dog_queue.dequeue()
elif request_type == None:
#which queue is older?
next_cat = self.cat_queue.peek().animal_id
next_dog = self.dog_queue.peek().animal_id
if next_cat < next_dog:
return self.cat_queue.dequeue()
else:
return self.dog_queue.dequeue()
else:
return None
def test_queue_peek():
letters = Queue()
assert not letters.peek()
letters.enqueue('A')
assert letters.peek() == 'A'
letters.enqueue('B')
assert letters.peek() == 'A'
def test_enqueue_two():
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
actual = q.peek()
expected = "apples"
assert actual == expected
def test_can_successfully_dequeue_out_of_a_queue_the_expected_value():
new_queue = Queue()
new_queue.enqueue('Three')
new_queue.enqueue('Two')
new_queue.enqueue('One')
expected = 'Three'
actual = new_queue.peek()
assert expected == actual
def test_can_successfully_enqueue_multiple_values_into_a_queue():
new_queue = Queue()
new_queue.enqueue('Three')
new_queue.enqueue('Two')
new_queue.enqueue('One')
expected = 'Three'
actual = new_queue.peek()
assert expected == actual
def test_peek():
q = Queue()
q.enqueue("apple")
q.enqueue("banana")
q.enqueue("cucumber")
actual = q.peek()
expected = "apple"
assert actual == expected
def test_stacks_and_queues_11 ():
queue = Queue()
queue.enquene('a')
queue.enquene('b')
queue.enquene('c')
actual = queue.peek()
expected = 'a'
assert actual == expected
def test_peek_queue():
q3 = Queue()
q3.enqueue(1)
q3.enqueue(3)
q3.enqueue(5)
q3.enqueue(7)
assert q3.peek() == 1
assert not q3.is_empty()
def test_peek_post_dequeue():
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
q.dequeue()
actual = q.peek()
expected = "bananas"
assert actual == expected
def traverse_breadth_first(self):
q = Queue()
q.enqueue(self.root)
while q.peek():
curr = q.dequeue()
yield curr.value
if curr.l_child:
q.enqueue(curr.l_child)
if curr.r_child:
q.enqueue(curr.r_child)
def test_stacks_and_queues_12 ():
queue = Queue()
queue.enquene('a')
queue.enquene('b')
queue.enquene('c')
queue.dequeue()
queue.dequeue()
queue.dequeue()
actual = queue.peek()
expected = None
assert actual == expected
def breadth_traverse(self):
""" Breadth-first traversal of binary tree """
output = []
q = Queue()
q.enqueue(self.root)
while q.peek():
curr = q.dequeue()
output.append(curr.value)
if curr.l_child:
q.enqueue(curr.l_child)
if curr.r_child:
q.enqueue(curr.r_child)
return output
def breadth_first_traverse(self, start_vert):
""" Returns a list of graph vertex values in breadth-first order
:param start_vert: Vertex object
:returns: list of vertex values
"""
q = Queue()
output = []
q.enqueue(start_vert)
start_vert.visited = True
while q.peek():
vert = q.dequeue()
output.append(vert.value)
for v, w in vert.adjacencies:
if not v.visited:
q.enqueue(v)
v.visited = True
self._reset_visited()
return output
def traverse(self, node, debug=False):
queue = Queue()
ret_baby = []
if not node:
return 'babies'
visited = {}
queue.enqueue(node)
while queue.peek():
current = queue.dequeue()
visited[current] = True
if current == 'this queue is empty buddy':
break
for baby_node in self._adjacency_list[current]:
if baby_node == None:
break
if not baby_node in visited:
queue.enqueue(baby_node)
ret_baby.append(current.value)
if debug:
breakpoint()
return ret_baby
def breadth_first(self, start):
"""This method does a breadth first traversal of a graph
Arguments:
node -- [starting poing of the traversal]
Returns:
[list] -- [a list of all connected nodes]
"""
explored = []
queue = Queue()
queue.enqueue(start)
while queue.peek() is not None:
node = queue.dequeue()
if node not in explored:
explored.append(node)
neighbors = self._graph[node]
for neighbor in neighbors:
queue.enqueue(neighbor[0])
return explored
def test_peek_queue_from_empty():
q7 = Queue()
assert q7.is_empty()
with pytest.raises(AttributeError):
q7.peek()
def test_can_successfully_peek_into_a_queue_seeing_the_expected_value():
new_queue = Queue()
new_queue.enqueue('Three')
expected = 'Three'
actual = new_queue.peek()
assert expected == actual
def test_queue_peek():
queue5 = Queue()
queue5.enqueue(5)
assert queue5.peek() == 5
assert queue5.back.val == 5
assert queue5.front.val == 5
def test_stacks_and_queues_14 ():
queue = Queue()
actual = queue.peek()
expected = None
assert actual == expected
def test_queue_peek_exception():
queue6 = Queue()
with pytest.raises(Exception) as excep:
queue6.peek()
assert "EmptyQueue" in excep
def test_peek_empty_queue():
queue = Queue()
with pytest.raises(EmptyQueueException):
queue.peek()
with pytest.raises(EmptyQueueException):
queue.dequeue()
def test_can_successfully_enqueue_into_a_queue():
new_queue = Queue()
new_queue.enqueue('One')
expected = 'One'
actual = new_queue.peek()
assert expected == actual
def test_peek_empty_queue():
q = Queue()
assert q.peek() == 'this queue is empty buddy'
def test_peek_when_empty():
q = Queue()
with pytest.raises(InvalidOperationError):
q.peek()
def test_queue_peek():
q = Queue()
q.enqueue('first value')
q.enqueue('second value')
assert q.peek() == 'first value'
def test_peek_on_empty_raises_exception():
new_queue = Queue()
expected = 'Exception'
actual = new_queue.peek()
assert expected == actual
