Python表示队列
It is also possible to use a list as a queue, where the first element added is the first element retrieved (“first-in, first-out”); however, lists are not efficient for this purpose. While appends and pops from the end of list are fast, doing inserts or pops from the beginning of a list is slow (because all of the other elements have to be shifted by one).
To implement a queue, use collections.deque which was designed to have fast appends and pops from both ends. For example:
>>> from collections import deque>>> queue = deque(["Eric", "John", "Michael"])>>> queue.append("Terry") # Terry arrives>>> queue.append("Graham") # Graham arrives>>> queue.popleft() # The first to arrive now leaves'Eric'>>> queue.popleft() # The second to arrive now leaves'John'>>> queue # Remaining queue in order of arrivaldeque(['Michael', 'Terry', 'Graham'])