How to Sort a Queue in Python

In computer programming, a queue is a list where elements are inserted from one end (the ‘rear’) and removed from the other end (the ‘front’). This operation follows the FIFO (First In, First Out) methodology.

Python doesn’t support direct sorting in a queue, but with some basic Python programming tricks, you can successfully sort a queue. This tutorial will guide you through the steps required to perform this task.

Step 1: Understanding Queues and SORTING

Before diving into queue sorting, it’s important to understand what a queue is and how sorting works in Python. Queues are data structures that store items in an ordered series based on the FIFO concept. You can visit here for a detailed overview.

Sorting is organizing items in some specific order (either descending or ascending). In Python, you can sort list items using list.sort() or sorted().

Step 2: Importing Required Libraries

Python’s built-in queue is actually a module that needs to be imported. Below is the basic command:

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import queue

Step 3: Initializing the Queue

Once you have imported the queue module, initialize the queue using the queue.Queue() function which is available in the queue module. Here’s how you can do that:

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import queue
q = queue.Queue()

Step 4: Add Items to the Queue

You can add items to the queue using the queue’s put() method. See the example below:

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q.put(5)
q.put(9)
q.put(1)
q.put(7)

Step 5: Sort Items in the Queue

Python does not directly support sorting a queue. So, you need to convert it into a list, sort the list, and then put elements back into the queue.

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# Empty the queue into a list
queue_items = []
while not q.empty():
    queue_items.append(q.get())
 
# Sort the list
queue_items.sort()
 
# Put the items back into the queue
for item in queue_items:
    q.put(item)

Step 6: Verify Sorted Items

Viewing the result by popping elements from the queue:

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while not q.empty():
    print(q.get())

You should get the following output:

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5
7
9

Full Code

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import queue
 
# Initialize the queue
q = queue.Queue()
 
# Add items to the queue
q.put(5)
q.put(9)
q.put(1)
q.put(7)
 
# Empty the queue into a list
queue_items = []
while not q.empty():
    queue_items.append(q.get())
 
# Sort the list
queue_items.sort()
 
# Put the items back into the queue
for item in queue_items:
    q.put(item)
 
# Print the sorted items
while not q.empty():
    print(q.get())

Conclusion

Sorting items in a queue may not have direct support in Python, but this tutorial has demonstrated a simple way to achieve it using basic Python commands. This method of converting the queue into a list, sorting the list, and then repopulating the queue opens up a lot of possibilities for managing and manipulating data in Python.