In Python, a built-in list data structure is called a module that implements multi-procedure and multi-consumer queues. In this article, we will learn Python’s built-in function queue. A queue is a data structure established on the
first in and first out (FIFO) rule when inserting and removing elements, whereas in stacks, as the name suggests, follow the
Last in and First Out (LIFO) rule.
A queue has two kinds of operations:
The procedure in which items are added to the end of the queue in an operation is called
enqueue and when the items removed from the beginning of the queue are called
dequeue operation. A queue in Python is usually fulfilled using the in-built list,
Queue from the
queue module, or deque from the
There are two open ends in the
queue: front and rear ends. They are used for different purposes to work with queue,
rear is the end that inserts items, and
front is used as the point of removal. Though the front and rear ends are treated as pointers, when the
queue is empty, both front and rear pointers are NULL. Furthermore, we cannot dequeue an empty queue, and we need at least one item to be available in the queue when we need to dequeue.
In the code example below, we will see how we can insert items in the queue and delete those items one by one from the queue.
Queue in Python
In the code sample below, we will learn how to add and delete items from the queue item list. We will first create a list of the vegetables, and then we will add the names of the vegetables one by one. Once all items are added using the
append() function, we will delete each item one by one using the
pop() function. Furthermore, we can see that the first item inserted in the list has been deleted first, which has confirmed that the queue works as the
first in and first out (FIFO) methodology.
import queue vegetables =  vegetables.append("Broccoli") vegetables.append("Potato") vegetables.append("Carrot") vegetables.append("Spinach") first_item = vegetables.pop(0) print(first_item) Second_item = vegetables.pop(0) print(Second_item) print(vegetables)
Broccoli Potato ['Carrot', 'Spinach']