Creating a list of stacks in python

Question

so I am trying to create a list of stack objects in Python. I have first created a class Stack that has simple methods that a Stack should have. I have then created another class called Stacks. I am trying to create a list of stacks. If a stack has more than 3 elements, it creates a new stack but I get an error when I try to display the elements. Could someone point out what I might be doing wrong here please?

class Stack:

    def __init__(self):
        self.items =  []

    def isEmpty(self):
        return self.items == []

    def push(self, item):
        self.items.append(item)

    def pop(self):
        return self.items.pop()

    def size(self):
        return len(self.items)

    def printStack(self):
        for item in reversed(self.items):
            print (item)


class Stacks:

    def __init__(self):
        self.stacks = []
        self.noOfStacks = 0
        self.itemsOnStack = 0

    def dev(self):
        self.stacks.append(Stack())
        # if len(self.stacks) != 0:
        #     self.noOfStacks += 1

    def push(self, item):
        if self.itemsOnStack > 3:
            self.dev()
        else:
            self.itemsOnStack += 1
            self.stacks[self.noOfStacks].push(item)

    def pop(self, stackNo):
        return self.stacks(noOfStacks).pop()

    def size(self):
        return len(self.stacks)

    def printtack(self, index):
        print (len(self.stacks(index)))
        self.stacks(index).printStack()


stacky = Stacks()
stacky.dev()
stacky.push(3)
stacky.printtack(0)

Make sure you post Python code with correct indentation. Otherwise you are introducing new problems into the code. — khelwood
– khelwood, Commented Dec 29, 2017 at 14:45
FWIW, collections.deque can be used as a stack, and it's generally a little faster than using a list. — PM 2Ring
– PM 2Ring, Commented Dec 29, 2017 at 14:49

Kent Shikama · Accepted Answer · 2017-12-29 14:39:31Z

1

Indexing lists in Python works by [] not (). Try

 def printtack(self, index):
    self.stacks[index].printStack()

answered Dec 29, 2017 at 14:39

Kent Shikama

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Comments

Albin Paul · Accepted Answer · 2017-12-29 14:53:24Z

0

One thing to note as kshikama said indexing should be done using [] not (),the other problem is using the len() method in the stack class u most override the __len__() method or as u have given use the size() method

class Stack:
    def __init__(self):
        self.items =  []

    def isEmpty(self):
        return self.items == []

    def push(self, item):
        self.items.append(item)

    def pop(self):
        return self.items.pop()

    def size(self):
        return len(self.items)

    def printStack(self):
        for item in reversed(self.items):
            print (item)

class Stacks:
    def __init__(self):
        self.stacks = []
        self.noOfStacks = 0
        self.itemsOnStack = 0

    def dev(self):
        self.stacks.append(Stack())
        #if len(self.stacks) != 0:
            #self.noOfStacks += 1

    def push(self, item):

        if self.itemsOnStack > 3:
            self.dev()
        else:
            self.itemsOnStack += 1
            self.stacks[self.noOfStacks].push(item)


    def pop(self, stackNo):
        return self.stacks(noOfStacks).pop()

    def size(self):
        return len(self.stacks)

    def printtack(self, index):
        print (self.stacks[index].size())
        self.stacks[index].printStack()
stacky = Stacks()
stacky.dev()
stacky.push(3)
stacky.printtack(0)

OUTPUT

1
3

answered Dec 29, 2017 at 14:53

Albin Paul

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1 Comment

paddy Over a year ago

Omg im such an idiot for using () as index instead of []. Thanks everyone above for helping me.

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