How To Create A Queue In Python?

In this tutorial, you will learn how to create a queue in python.

To create a queue in Python, you can make use of the built-in queue module, which provides a Queue class that implements the necessary functionality.

Here’s how you can create a queue and use its methods.

Step 1: Import the queue module

import queue

Step 2: Create an instance of the Queue class

my_queue = queue.Queue()

Now, let’s explore the methods available for the Queue class.

put(item) method

This method adds an item to the queue.

The item parameter represents the object you want to add to the queue.

If the queue is full, this method will block until there is space available.

For Example:

python my_queue.put("Item 1") my_queue.put(42)

get() method: How To Create A Queue In Python?

This method removes and returns the item at the front of the queue.

If the queue is empty, this method will block until an item becomes available.

For Example:

python item = my_queue.get() print(item)

Output

empty() method

This method checks if the queue is empty.

Returns True if the queue is empty, False otherwise.

For Example:

python is_empty = my_queue.empty() 
print(is_empty)

Output

qsize() method: How To Create A Queue In Python?

This method returns the current size of the queue.

For Example:

python size = my_queue.qsize() print(size)

Output

task_done() method

This method is used to indicate that a previously enqueued task has been completed.

Each call to get() should be followed by a call to task_done() for each item retrieved.

If the number of task_done() calls equals the number of items retrieved, subsequent calls to join() will return immediately.

For Example:

python my_queue.get() my_queue.task_done()

join() method: How To Create A Queue In Python?

This method blocks until all the items in the queue have been processed and marked as done.

You can use it to ensure that all items in the queue have been consumed.

For Example:

python my_queue.join()

By utilizing these methods, you can create and manipulate a queue in Python.

The put() and get() methods allow you to add and retrieve items, respectively.

While the empty() and qsize() methods help you check the queue’s status.

Additionally, the task_done() and join() methods provide synchronization mechanisms for handling tasks in the queue.

How To Create A Queue In Python?

Here’s an example demonstrating the usage of these methods:

import queue

my_queue = queue.Queue()

my_queue.put("Item 1")
my_queue.put("Item 2")
my_queue.put("Item 3")

print(my_queue.qsize())  # Output: 3

item = my_queue.get()
print(item)  # Output: Item 1

print(my_queue.empty())  # Output: False

my_queue.task_done()

my_queue.join()

print(my_queue.empty())  # Output: True

In the example above, we create a queue using the Queue() class from the queue module.

We add three items to the queue using put(), retrieve the first item using get(), check if the queue is empty using empty(), indicate that a task is done using task_done(), and wait for all items to be processed using join().

Here’s an example that demonstrates the usage of the queue module to create a simple queue for processing customer service requests:

import queue

# Create an instance of the Queue class
service_queue = queue.Queue()

# Enqueue customer service requests
service_queue.put("Request 1")
service_queue.put("Request 2")
service_queue.put("Request 3")

# Dequeue and process customer service requests
while not service_queue.empty():
    request = service_queue.get()
    print("Processing request:", request)
    # Perform the necessary processing for each request

print("All requests have been processed.")

Output

In this example, we start by creating an instance of the Queue class using queue.Queue().

This creates an empty queue for storing customer service requests.

We then enqueue three customer service requests using the put() method.

A string represents each request.

Next, we use a while loop to continuously dequeue requests from the queue until it becomes empty.

Inside the loop, we retrieve a request using the get() method and assign it to the request variable.

We then perform the necessary processing for each request, which, in this case, is simply printing the request.

The loop continues until the queue becomes empty.

This indicates that the program has processed all the requests.

Finally, we print a message stating that all requests have been processed.

Learn more about advanced python data structures here.