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pythonqueuedeque

What is the difference between deque( [1,2,3] ) and deque.append( [1,2,3] )?

I have noticed that the following incurs an iterable error.

q = deque([1,2,3])
x, y, z = q.popleft()
# TypeError: 'int' object is not iterable

But the code below works which I thought the same operation:

q = deque()
deque.append([1,2,3])
x, y, z = q.popleft()

What is the difference between the two ways above?

Thanks for your help in advance.

Solution

  • q.popleft() returns the first element of the deque. In the first case it is int and in the second it is a list of ints. You should write in the first case: x, y, z = q.