Python Basics: Detailed use of deque (for manipulating elements at both ends of the list)

Create a two-way queue

Import COLLECTIONSD = Collections.deque ()

Append (add an element to the right)

Import COLLECTIONSD = Collections.deque () d.append (1) d.append (2) print (d) #输出: Deque ([1, 2])

Appendleft (add an element to the left)

Import COLLECTIONSD = Collections.deque () d.append (1) d.appendleft (2) print (d) #输出: Deque ([2, 1])

Clear (Empty queue)

Import COLLECTIONSD = Collections.deque () d.append (1) d.clear () print (d) #输出: Deque ([])

Copy (shallow copy)

Import COLLECTIONSD = Collections.deque () d.append (1) new_d = D.copy () print (new_d) #输出: Deque ([1])

Count (returns the number of occurrences of the specified element)

Import COLLECTIONSD = Collections.deque () d.append (1) d.append (1) Print (D.count (1)) #输出: 2

Extend (extends the element of a list from the right side of the queue)

Import COLLECTIONSD = Collections.deque () d.append (1) d.extend ([3,4,5]) print (d) #输出: Deque ([1, 3, 4, 5])

Extendleft (extends the element of a list from the left side of the queue)

Import COLLECTIONSD = Collections.deque () d.append (1) d.extendleft ([3,4,5]) print (d) # # #输出: Deque ([5, 4, 3, 1])

Index (Find the index position of an element)

Import COLLECTIONSD = Collections.deque () d.extend ([' A ', ' B ', ' C ', ' d ', ' e ']) print (d) Print (D.index (' e ')) Print (D.index ( ' C ', 0,3))  #指定查找区间 # Output: deque ([' A ', ' B ', ' C ', ' d ', ' E ']) #     4#     2

Insert (Inserts an element at the specified location)

Import COLLECTIONSD = Collections.deque () d.extend ([' A ', ' B ', ' C ', ' d ', ' e ']) D.insert (2, ' Z ') print (d) #输出: deque ([' A ', ' B ') , ' Z ', ' C ', ' d ', ' e '])

Pop (Gets the rightmost element and deletes it in the queue)

Import COLLECTIONSD = Collections.deque () d.extend ([' A ', ' B ', ' C ', ' d ', ' e ']) x = D.pop () print (x,d) #输出: E deque ([' A ', ' B ', ' C ', ' d '])

Popleft (Gets the leftmost element and deletes it in the queue)

Import COLLECTIONSD = Collections.deque () d.extend ([' A ', ' B ', ' C ', ' d ', ' e ']) x = D.popleft () print (x,d) #输出: A deque ([' B ', ' C ', ' d ', ' e '])

Remove (removes the specified element)

Import COLLECTIONSD = Collections.deque () d.extend ([' A ', ' B ', ' C ', ' d ', ' e ']) d.remove (' C ') print (d) #输出: deque ([' A ', ' B ', ' d ', ' e '])

Reverse (queue reversal)

Import COLLECTIONSD = Collections.deque () d.extend ([' A ', ' B ', ' C ', ' d ', ' e ']) D.reverse () print (d) #输出: deque ([' E ', ' d ', ' C ' , ' B ', ' a '])

Rotate (Put the right element on the left)

Import COLLECTIONSD = Collections.deque () d.extend ([' A ', ' B ', ' C ', ' d ', ' e ']) d.rotate (2)   #指定次数, default 1 times print (d) # Output: Deque ([' d ', ' e ', ' A ', ' B ', ' C ')

Python Basics: Detailed use of deque (for manipulating elements at both ends of the list)