How to check deque length in Python

In Python, deque (double-ended queue) is a data structure provided by the deque class in the collections module, which supports fast insertion and deletion from both ends. If you want to check the length of a deque, you can use the built-in len() function, which is a simple and effective approach.

Below is a specific example demonstrating how to create a deque, add elements to it, and check its length:

python
from collections import deque

# Create an empty deque
d = deque()

# Add elements to the deque
d.append('a')
d.append('b')
d.appendleft('c')  # Add an element to the left
d.append('d')

# Print the deque
print("Current deque content:", list(d))

# Check the length of the deque
length = len(d)
print("Length of deque is:", length)

In this example, I first imported the deque class from the collections module and created a deque object named d. Then, I used the append() method to add two elements ('a' and 'b') to the right end of the deque, and the appendleft() method to add one element ('c') to the left. Finally, I added another element ('d') to the right end.

By calling len(d), we can obtain the current length of the deque, which outputs 4 here because the deque contains four elements.

This method is straightforward and ideal for quickly checking the length of a deque when needed.