In this tutorial, we will look at how to count the frequency of a value in a 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 get element frequency in 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 count the occurrences of a value in a deque in Python, use the deque count()
function. Pass the value as an argument.
The following is the syntax –
# count occurrences of "x" in deque "queue" queue.count(x)
It returns the number of elements in the deque that are equal to x
.
Examples
Let’s now look at some examples of using the above syntax –
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Example 1 – Count occurrences of a value deque
First, let’s create a deque with some elements.
from collections import deque # create a deque queue = deque([1, 2, 3, 4, 3, 5, 7]) # print the deque print(queue)
Output:
deque([1, 2, 3, 4, 3, 5, 7])
Here, we imported the deque
class from the collections
module and created a deque object, queue
with some numbers. You can see that the number 3
occurs two times in the above deque.
Now, let’s now count the occurrences of the value 3
in the above deque using code.
# count occurrences of 3 print(queue.count(3))
Output:
2
Here, we used the deque count()
function to get the frequency of the value 3
in the above deque. It returns 2
which is the number of times 3
occurs in the deque, queue
.
Example 2 – Count occurrences of a value not present in a deque
Let’s now try to find the frequency of a value not present in the deque.
We’ll use the same deque from above and pass 6
as the argument (the value 6
is not present in the deque).
# count occurrences of 6 print(queue.count(6))
Output:
0
We get 0 as the output because there are no values equal to 6
in the given deque object.
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- Python – Get Index of a Value in Deque
- Python – Remove Element by Value in Deque
- Python – Remove all elements from a deque (clear deque)
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