Stack, Queue data structures - AndrewMZ6/Python_cheat_sheet Wiki

Stack

Stack is LIFO (last in first out) data structure which can be made using python list and two of it's methods - append and 'pop`.
Adding to stack:

stack = []
stack.append('some_string')
stack.append(90)

Getting and removing element from the end of the stack

elem = stack.pop()

Queue

Queue is FIFO (first in first out) data structure is similar to stack but getting elements must be done from the beginning of the list

queue = []
queue.append('some_string')
queue.append(90)

Getting and removing element from the beginning of the queue

elem = queue.pop(0)

pop(0) returns the element with index 0 and removes it from queue object.
Here's my implementation of Queue as class

class Queue:
	"""
		adding elements:
		[] <- 73
		[73]

		[73] <- 771
		[73, 771]

		[73, 771] <- 80
		[73, 771, 80]

		getting elements:
		[73, 771, 80] -> 73
		[771, 80]
		
		[771, 80] -> 771
		[80]

		[80] -> 80
		[]
	"""
	def __init__(self):
		self.queue = []

	def add_el(self, *args):
		self.queue.extend(args)

	def get_el(self):
		return self.queue.pop(0)

	def __str__(self):
		return str(self.queue)

q = Queue()
q.add_el(1, 0, 'goo', (1, 2, 3))

print(f"q = {q}")

v = q.get_el()
print(f"q = {q}, v = {v}")

v = q.get_el()
print(f"q = {q}, v = {v}")

v = q.get_el()
print(f"q = {q}, v = {v}")

v = q.get_el()
print(f"q = {q}, v = {v}")

v = q.get_el()
print(f"q = {q}, v = {v}")

output:

q = [1, 0, 'goo', (1, 2, 3)]
q = [0, 'goo', (1, 2, 3)], v = 1
q = ['goo', (1, 2, 3)], v = 0
q = [(1, 2, 3)], v = goo
q = [], v = (1, 2, 3)
Traceback (most recent call last):
  File "E:\Code\Python\test20.py", line 52, in <module>
    v = q.get_el()
  File "E:\Code\Python\test20.py", line 30, in get_el
    return self.queue.pop(0)
IndexError: pop from empty list

Changing method's get_el body to return self.queue.pop() gives class representating stack

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