Learn Python – Basic Day 2

Python Syntax

• Indentation: Python uses indentation to define blocks of code. A block of code is a group of statements that should be treated as a unit.
  • Example:

  if 5 > 2:
      print("Five is greater than two!")
  

• Comments: Comments are used to explain the code and make it more readable. Python ignores comments when running the code.
  • Example:

  # This is a comment
  print("Hello, World!")
  

Python Operators

• Arithmetic Operators: Arithmetic operators are used to perform arithmetic operations like addition, subtraction, multiplication, and division.
  • Example:

  x = 5
  y = 2
  print(x + y)
  print(x - y)
  print(x * y)
  print(x / y)
  

• Comparison Operators: Comparison operators are used to compare two values.
  • Example:

  x = 5
  y = 2
  print(x == y)
  print(x != y)
  print(x > y)
  print(x < y)
  print(x >= y)
  print(x <= y)
  

Python Data Structures

• Lists: A list is a collection of items that are ordered and changeable.
  • Example:

  thislist = ["apple", "banana", "cherry"]
  print(thislist)
  

• Tuples: A tuple is a collection of items that are ordered and unchangeable.
  • Example:

  thistuple = ("apple", "banana", "cherry")
  print(thistuple)
  

• Dictionaries: A dictionary is a collection of items that are unordered, changeable, and indexed by keys.
  • Example:

  thisdict = {
      "brand": "Ford",
      "model": "Mustang",
      "year": 1964
  }
  print(thisdict)
  

Interactive Session:

• Questions and topics for discussion:
  • What are the different types of operators in Python?
  • What are the different data structures in Python?
  • Can you think of any real-life situations where you would use lists, tuples, or dictionaries?

Quiz:

• Questions and Answers:

  1. What is indentation in Python?

     • A) The amount of space at the beginning of a line of code
     • B) The amount of space at the end of a line of code
     • C) The amount of space between two lines of code
     • Explanation: Indentation is the amount of space at the beginning of a line of code. Python uses indentation to define blocks of code. For example, in the code if 5 > 2: print("Five is greater than two!"), the print statement is indented to show that it is part of the if block.

  2. What are comments in Python?

     • A) Comments are used to explain the code and make it more readable*
     • B) Comments are used to make the code run faster
     • C) Comments are used to make the code run slower
     • Explanation: Comments are used to explain the code and make it more readable. Python ignores comments when running the code. For example, in the code # This is a comment print("Hello, World!"), the # This is a comment is a comment and is ignored by Python.

  3. What are the different types of operators in Python?

     • A) Arithmetic operators and comparison operators*
     • B) Arithmetic operators and logical operators
     • C) Comparison operators and logical operators
     • Explanation: There are several types of operators in Python, including arithmetic operators (e.g., +, -, *, /), comparison operators (e.g., ==, !=, >, <, >=, <=), and logical operators (e.g., and, or, not).

  4. What are the different data structures in Python?

     • A) Lists, tuples, and dictionaries*
     • B) Lists, arrays, and dictionaries
     • C) Arrays, tuples, and dictionaries
     • Explanation: Python has several built-in data structures, including lists, tuples, and dictionaries. A list is a collection of items that are ordered and changeable. A tuple is a collection of items that are ordered and unchangeable. A dictionary is a collection of items that are unordered, changeable, and indexed by keys.

Mini-Project: Shopping List

• Objective: Create a program that allows the user to create and modify a shopping list.
• Requirements:
  • The user should be able to add items to the shopping list.
  • The user should be able to remove items from the shopping list.
  • The user should be able to view the shopping list.
• Steps to Complete the Project:
  • Write the code to display the options to the user (add item, remove item, view list, exit).
  • Write the code to add an item to the shopping list.
  • Write the code to remove an item from the shopping list.
  • Write the code to view the shopping list.
• Source Code:

# Step 1: Create an empty shopping list
shopping_list = []

# Step 2: Display the options to the user
while True:
    print("\nOptions:")
    print("1. Add item")
    print("2. Remove item")
    print("3. View list")
    print("4. Exit")
    option = int(input("Enter an option (1-4): "))
    
    # Step 3: Add item to the shopping list
    if option == 1:
        item = input("Enter the item to add: ")
        shopping_list.append(item)
    # Step 4: Remove item from the shopping list
    elif option == 2:
        item = input("Enter the item to remove: ")
        if item in shopping_list:
            shopping_list.remove(item)
        else:
            print("Item not in list")
    # Step 5: View the shopping list
    elif option == 3:
        print("Shopping List:")
        for item in shopping_list:
            print(item)
    # Step 6: Exit the program
    elif option == 4:
        break
    else:
        print("Invalid option. Please try again.")

In this code:

• Step 1: We create an empty shopping list.
• Step 2: We display the options to the user and get their input.
• Step 3: We add an item to the shopping list.
• Step 4: We remove an item from the shopping list.
• Step 5: We view the shopping list.
• Step 6: We exit the program.