How to use deque to retain the latest N elements in python (code)

The content of this article is about the implementation method (code) of using deque to retain the latest N elements in Python. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you. .

1. Requirements

Make a limited number of historical records.

2. Solution

deque(maxlen=N), create a fixed-length queue, and when new records are added and the queue is full, the oldest record will be automatically removed. .

Code:

from collections import deque

q=deque(maxlen=3)

q.append(1)
q.append(2)
q.append(3)
print(q)
q.append(4)
print(q)
q.append(5)
print(q)

Result:

deque([1, 2, 3], maxlen=3)
deque([2, 3, 4], maxlen=3)
deque([3, 4, 5], maxlen=3)

If you do not specify the size of the queue, you will get an unbounded queue, and you can perform add and pop operations at both ends,

Code:

from collections import deque

q=deque()
q.append(1)
q.append(2)
q.append(3)
q.append(4)
print(q)
q.appendleft(5)
print(q)
print(q.pop())
print(q)
print(q.popleft())
print(q)

Result:

deque([1, 2, 3, 4])
deque([5, 1, 2, 3, 4])
4
deque([5, 1, 2, 3])
5
deque([1, 2, 3])

The above is the detailed content of How to use deque to retain the latest N elements in python (code). For more information, please follow other related articles on the PHP Chinese website!