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Python Basics Part 2

Title: Python for Beginners - Part 2

Title: Python Data Structures: Mastering Lists, Tuples, and Dictionaries

Lists: The Flexible Organizers

  • What they are: Lists are ordered, mutable collections of items. Think of them as changeable shopping lists.
  • Creating a list:
    my_numbers = [1, 2, 3, 4]
my_friends = ["Alice", "Bob", "Charlie"]
  • Accessing items: Use zero-based indexing 
    print(my_numbers[0])  # Output: 1
  • Changing items:
    my_friends[1] = "Sarah"
  • Common methods:
    • list.append(item) – Adds an item to the end
    • list.insert(index, item) – Inserts an item at a specific position
    • list.remove(item) – Removes the first occurrence of an item

Tuples: The Immutable Cousins

  • What they are: Tuples are ordered, immutable collections of items. Think of them as fixed sets of coordinates.
  • Creating a tuple:
    coordinates = (10, 20)
website_info = ("Python 101", "https://python101.com")
  • Accessing items: Same indexing as lists
  • Why immutable? Good for data that shouldn't change (like coordinates, configuration settings) and can make your code a bit safer.

Dictionaries: Key-Value Superstars

  • What they are: Dictionaries store key-value pairs, like real-world dictionaries. Keys must be unique and immutable.
  • Creating a dictionary:
    student = {"name": "Alice", "age": 30, "courses": ["Math", "Science"]}
  • Accessing values:
    print(student["name"])  # Output: Alice
  • Changing values:
    student["age"] = 31
  • Adding items:
    student["city"] = "New York"

Let's Build Something Practical

How about a contact book application?

contacts = {
    "Alice": {"phone": "123-456-7890", "email": "alice@email.com"},
    "Bob": {"phone": "987-654-3210", "email": "bob@email.com"}
}

def add_contact():
    # Code to get name, phone, email...

def find_contact():
    # Code to search by name...

# Simple menu for the user...

Key Takeaways

  • Choose wisely:
    • Lists for ordered, changeable data
    • Tuples for fixed, unchangeable data
    • Dictionaries for mapping keys to values

Continue Your Exploration

  • Advanced list operations: Slicing, sorting, list comprehensions
  • More dictionary methods: items(), keys(), values()
  • Sets: Unordered collections of unique items (great for removing duplicates)
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