5.11 Simulating Stacks with Lists

  • Python does not have a built-in stack type.
  • Can think of a stack as a constrained list.
  • Push using list method append.
  • Pop using list method pop with no arguments to get items in last-in, first-out (LIFO) order.
In [1]:
stack = []
In [2]:
stack.append('red')
In [3]:
stack
Out[3]:
['red']
In [4]:
stack.append('green')
In [5]:
stack
Out[5]:
['red', 'green']
In [6]:
stack.pop()
Out[6]:
'green'
In [7]:
stack
Out[7]:
['red']
In [8]:
stack.pop()
Out[8]:
'red'
In [9]:
stack
Out[9]:
[]
In [10]:
stack.pop()

------------------------------------------------------------------------
IndexError                             Traceback (most recent call last)
<ipython-input-10-415460d3b717> in <module>
----> 1 stack.pop()

IndexError: pop from empty list
  • Also can use a list to simulate a queue.
  • Items are retrieved from queues in first-in, first-out (FIFO) order.

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