Python .clear()

The .clear() method in Python’s collections.deque class removes all elements from the deque, leaving it empty. It’s useful when the contents of the deque need to be cleared without deleting the object itself.

The method modifies the deque in place and returns None. Its time complexity is O(n) since it removes elements one by one.

Syntax

deque.clear()

Parameters:

• None: This method does not take any parameters as it simply resets the deque to empty.

Return value:

The return value of .clear() should be a check to determine if the deque is empty. This can be done using an if statement with a return value of true when checked if empty or simply a print() statement to output the length of the deque.

Example 1: Clearing All Elements from a Deque

In this example, the .clear() method removes every element from the deque, and an if statement checks whether it is empty afterward:

from collections import deque

# Create a deque
cars = deque(["toyota", "suzuki", "honda"])
print(f"Initial deque is as follows: {cars}")

# Clearing the deque
cars.clear()

# If statement to check if the deque has been sucessfully cleared
if not cars:
  print("the deque is empty")

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The output of this code is:

Initial deque: deque(['Toyota', 'Suzuki', 'Honda'])
The deque is empty.

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Codebyte Example: Clearing Completed Tasks

In this example, a deque keeps track of recent tasks in a to-do list. After all tasks are completed, the .clear() method is used to empty the deque and prepare it for new tasks:

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