Python List as Queues(First-in, First-Out)

queues.md

In this article we will learn how to use python list(built-in data structure) as Queues.

Python List as Queues(First-in, First-Out)

• import collections.deque
• To add an item, append()
• To remove an item, popleft()

from collections import deque
queue = deque() 

queue.append('black') #first-in
queue.append('red')
queue.append('yellow') 
queue.append('green') #last-in

>>> queue

deque(['black', 'red', 'yellow', 'green'])

>>> queue.popleft() # first-out 

'black'

>>> queue.popleft()

'red'

>>> queue.popleft()

'yellow'

>>> queue.popleft()

'green'

>>> queue.popleft()

---------------------------------------------------------------------------

IndexError                                Traceback (most recent call last)

<ipython-input-10-e488fdbdaa60> in <module>()
----> 1 queue.popleft()


IndexError: pop from an empty deque