How to check deque length in Python

Question

How to check a deque's length in python?

I don't see they provide deque.length in Python...

http://docs.python.org/tutorial/datastructures.html

from collections import deque queue = deque(["Eric", "John", "Michael"]) 

How to check the length of this deque?

and can we initialize like

queue = deque([])   #is this length 0 deque? 

Answer 1

len(queue) should give you the result, 3 in this case.

Specifically, len(object) function will call object.__len__ method [reference link]. And the object in this case is deque, which implements __len__ method (you can see it by dir(deque)).

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queue= deque([])   #is this length 0 queue? 

Yes it will be 0 for empty deque.

Answer 2

it is simple just use .qsize() example:

a=Queue() a.put("abcdef") print a.qsize() #prints 1 which is the size of queue 

The above snippet applies for Queue() class of python. Thanks @rayryeng for the update.

for deque from collections we can use len() as stated here by K Z.