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Detailed introduction to python3 deque (two-way queue)

Mar 23, 2017 pm 02:45 PM

Create a two-way queue

import collections
d = collections.deque()

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append(Add an element to the right)

import collections
d = collections.deque()
d.append(1)
d.append(2)print(d)#输出：deque([1, 2])

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appendleft(Add an element to the left)

import collections
d = collections.deque()
d.append(1)
d.appendleft(2)print(d)#输出：deque([2, 1])

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clear(clear the queue)

import collections
d = collections.deque()
d.append(1)
d.clear()print(d)#输出：deque([])

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copy(shallow copy)

import collections
d = collections.deque()
d.append(1)
new_d = d.copy()print(new_d)#输出：deque([1])

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count(return the number of occurrences of the specified element)

import collections
d = collections.deque()
d.append(1)
d.append(1)print(d.count(1))#输出：2

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extend(extend the elements of a list from the right side of the queue)

import collections
d = collections.deque()
d.append(1)
d.extend([3,4,5])print(d)#输出：deque([1, 3, 4, 5])

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extendleft (Extend elements of a list from the left side of the queue)

import collections
d = collections.deque()
d.append(1)
d.extendleft([3,4,5])print(d)#
# #输出：deque([5, 4, 3, 1])

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index (Find the index position of an element)

import collections
d = 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#输出：deque(['a', 'b', 'c', 'd', 'e'])#     4#     2

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insert (Insert an element at the specified position)

import collections
d = collections.deque()
d.extend(['a','b','c','d','e'])
d.insert(2,'z')print(d)#输出：deque(['a', 'b', 'z', 'c', 'd', 'e'])

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pop (get the rightmost element and delete it in the queue)

import collections
d = collections.deque()
d.extend(['a','b','c','d','e'])
x = d.pop()print(x,d)#输出：e deque(['a', 'b', 'c', 'd'])

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popleft (get the leftmost element and delete it in the queue)

import collections
d = collections.deque()
d.extend(['a','b','c','d','e'])
x = d.popleft()print(x,d)#输出：a deque(['b', 'c', 'd', 'e'])

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remove (delete the specified element)

import collections
d = collections.deque()
d.extend(['a','b','c','d','e'])
d.remove('c')print(d)#输出：deque(['a', 'b', 'd', 'e'])

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reverse (queue reversal)

import collections
d = collections.deque()
d.extend(['a','b','c','d','e'])
d.reverse()print(d)#输出：deque(['e', 'd', 'c', 'b', 'a'])

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rotate (put the right element to the left)

import collections
d = collections.deque()
d.extend(['a','b','c','d','e'])
d.rotate(2)   #指定次数，默认1次print(d)#输出：deque(['d', 'e', 'a', 'b', 'c'])

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