Python – Remove all elements from a deque (clear deque)

In this tutorial, we will look at how to remove all the elements from a deque (clear/empty the deque) in Python with the help of some examples.

deque in Python

The collections module in Python comes with a deque class that you can use to implement a stack or queue data structure in Python. Deques support thread-safe, memory efficient appends and pops from either side of the deque with approximately the same O(1) performance in either direction.

In simple terms, you can think of a deque in Python as a list-like data structure but with efficient insertion and removal of items from either end (left and right). This makes them very useful when implementing a stack or queue functionality in Python.

How to append an element to a deque in Python?

The deque class comes with a number of built-in functions to help perform common operations (like adding and removing elements).

To remove all the elements from a deque in Python, use the deque clear() function. The following is the syntax –

# clear deque "queue"
queue.clear()

It removes all the values from the deque (clears/empties the deque) leaving it with a length of 0.

Examples

Let’s now look at some examples of using the above syntax –

Example 1 – Remove all values from a non-empty deque

First, let’s create a deque with some elements.

from collections import deque

# create a deque
queue = deque([1, 2, 3])
# print the deque
print(queue)

Output:

deque([1, 2, 3])

Here, we imported the deque class from the collections module and created a deque object, queue with three elements – 1, 2, and 3.

Now, let’s now remove all the elements from the deque created above.

# clear the deque
queue.clear()
# print the deque
print(queue)

Output:

deque([])

Here, we used the deque clear() function to remove all the elements from the deque queue.

Example 2 – Remove all values from a non-empty bounded deque

Let’s now create a bounded deque (deque object with a specified maxlen which defines the maximum number of values that it can store).

# create a bounded deque
queue = deque([1, 2, 3], maxlen=4)
# print the deque
print(queue)

Output:

deque([1, 2, 3], maxlen=4)

Here, we created a bounded deque with maxlen 4 and three elements inside it. Now, let’s remove all the elements from this deque using the clear() function.

# clear the deque
queue.clear()
# print the deque
print(queue)

Output:

deque([], maxlen=4)

We get an empty deque with maxlen set to 4.

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