Python 教程：Deque

Deque（或双端队列）具有从两端添加和删除元素的功能。 Deque 模块是集合库的一部分。它具有添加和删除元素的方法，可以直接使用参数调用。在以下程序中，导入模块collection并声明双端队列。不需要任何类，只需使用这些方法的内置实现即可。

参数通过以下代码实现 -

import collections
# Create a deque
DoubleEnded = collections.deque(["Mon","Tue","Wed"])
print (DoubleEnded)

# Append to the right
print("Adding to the right: ")
DoubleEnded.append("Thu")
print (DoubleEnded)

# append to the left
print("Adding to the left: ")
DoubleEnded.appendleft("Sun")
print (DoubleEnded)

# Remove from the right
print("Removing from the right: ")
DoubleEnded.pop()
print (DoubleEnded)

# Remove from the left
print("Removing from the left: ")
DoubleEnded.popleft()
print (DoubleEnded)

# Reverse the dequeue
print("Reversing the deque: ")
DoubleEnded.reverse()
print (DoubleEnded)

运行上面的代码示例，得到以下结果 -

deque(['Mon', 'Tue', 'Wed'])
Adding to the right: 
deque(['Mon', 'Tue', 'Wed', 'Thu'])
Adding to the left: 
deque(['Sun', 'Mon', 'Tue', 'Wed', 'Thu'])
Removing from the right: 
deque(['Sun', 'Mon', 'Tue', 'Wed'])
Removing from the left: 
deque(['Mon', 'Tue', 'Wed'])
Reversing the deque: 
deque(['Wed', 'Tue', 'Mon'])