What Is Stack Data Structure in Python?

//

Heather Bennett

A stack is a commonly used data structure in computer science that follows the Last-In-First-Out (LIFO) principle. In other words, the last element added to the stack is the first one to be removed. This data structure can be implemented in various programming languages, including Python.

Creating a Stack in Python

In Python, you can easily create a stack using built-in data structures such as lists. Let’s see how:

stack = []

The above code creates an empty list called ‘stack’ which will serve as our stack data structure.

Stack Operations

Stacks typically support three primary operations: push, pop, and peek. Let’s look at each of these operations:

  • Push: Adding elements to the stack is known as pushing. To push an element onto the stack in Python, we can use the append() method of lists.
  •   # Pushing elements onto the stack
      stack.append(5)
      stack.append(10)
      
  • Pop: Removing elements from the top of the stack is called popping.

    In Python, we can use the pop() method of lists to accomplish this.

  •   # Popping elements from the stack
      popped_element = stack.pop()
      
  • Peek: Peek allows us to access the topmost element of the stack without removing it. In Python, we can simply access it using index -1.
  •   # Peeking at the topmost element
      top_element = stack[-1]
      

Stack Implementation Example

Let’s see a practical example of implementing a stack in Python. Suppose we want to reverse a given string using a stack:

def reverse_string(string):
    stack = []
    reversed_string = ""
    
    # Push each character onto the stack
    for char in string:
        stack.append(char)
    
    # Pop each character from the stack to construct the reversed string
    while len(stack) > 0:
        reversed_string += stack.pop()
    
    return reversed_string

# Test the function
print(reverse_string("Hello, World!"))

The output of this code will be: “!dlroW ,olleH”. Here, we use a stack to push all the characters of the given string and then pop them one by one to construct the reversed string.

Conclusion

In summary, a stack is a powerful data structure that follows the LIFO principle. It can be easily implemented in Python using built-in data structures like lists.

Understanding stacks and their operations is essential for solving various algorithmic problems efficiently. Now that you have learned about stacks, you can start incorporating this knowledge into your Python programs.

Discord Server - Web Server - Private Server - DNS Server - Object-Oriented Programming - Scripting - Data Types - Data Structures

Privacy Policy