Python Tutorial Summary

Introduction

• Instructor: Mosh Hamedani
• Objective: Learn Python programming from scratch for data science, machine learning, or web development.
• No prior knowledge required
• Purpose: To equip learners with basic Python programming skills
• Applications of Python:
  • Machine Learning and AI
  • Web Development (using Django)
  • Automation

Setting Up Python Environment

Download Python

• Website: python.org
• Steps:
  • Go to Downloads and select the latest version
  • Install the package
  • On Windows: Check the box to add Python to PATH
  • Follow the installation steps

Install Code Editor

• Recommended Editor: PyCharm (from JetBrains)
• Steps:
  • Download PyCharm (Community Edition)
  • Install the package
  • Configure initial settings (skip remaining and set defaults)
  • Create a new project (e.g., hello_world)

Writing and Running Python Code

Hello World Program

• Create file: New Python file (app.py)
• Code:

  print("Hello, World!")
  

• Run: Execute the program to print the output in terminal

Variables in Python

• Definition: Used to temporarily store data

• Example:

  age = 20
  print(age)
  age = 30
  print(age)
  

• Types of Variables:

  • Integer
  • Float
  • String
  • Boolean

• Example for different types:

  price = 19.95  # float
  first_name = "Mosh"  # string
  is_online = True  # boolean
  

• Exercise: Declare variables for hospital check-in

User Input

• Function: input() to receive user input
• Example:

  name = input("What is your name? ")
  print("Hello " + name)
  

• Type Conversion Functions:
  • int(), float(), bool(), str()
• Example: Calculate user’s age from birth year

  birth_year = int(input("Enter your birth year: "))
  age = 2020 - birth_year
  print(age)
  

Exercise

• Write a basic calculator program to add two numbers
• Solution:

  first = float(input("Enter first number: "))
  second = float(input("Enter second number: "))
  sum = first + second
  print("Sum is: " + str(sum))
  

Working with Strings

• Common Methods:
  • .upper(), .lower(), .find(), .replace()
• Examples:

  course = "Python for Beginners"
  print(course.upper())
  print(course.find("for"))
  print(course.replace("Beginners", "Experts"))
  print("Python" in course)
  

Arithmetic Operations

• Operators: +, -, *, /, //, %, **
• Example:

  print(10 + 3)
  print(10 - 3)
  print(10 * 3)
  print(10 / 3)
  print(10 // 3)
  print(10 % 3)
  print(10 ** 3)
  

• Augmented Assignment:

  x = 10
  x += 3  # same as x = x + 3
  print(x)
  

Operator Precedence and Parentheses

• Example:

  x = 10 + 3 * 2  # Result: 16
  x = (10 + 3) * 2  # Result: 26
  

Comparison and Logical Operators

• Comparison: >, >=, <, <=, ==, !=
• Logical: and, or, not
• Examples:

  price = 25
  print(price > 10 and price < 30)
  print(price > 10 or price < 30)
  print(not price > 10)
  

Conditional Statements

• Structure:

  • if, elif, else

• Example:

  temperature = 35
  if temperature > 30:
      print("It's a hot day")
      print("Drink plenty of water")
  elif temperature > 20:
      print("It's a nice day")
  elif temperature > 10:
      print("It's a bit cold")
  else:
      print("It's cold")
  print("Done")
  

• Exercise: Write a weight converter program

Loops

While Loop

• Example:

  i = 1
  while i <= 5:
      print(i)
      i += 1
  

• Example with string multiplication:

  i = 1
  while i <= 10:
      print(i * '*')
      i += 1
  

For Loop

• Example:

  numbers = [1, 2, 3, 4, 5]
  for item in numbers:
      print(item)
  

Range Function

• Usage: Generates a sequence of numbers
• Examples:

  for number in range(5):
      print(number)  # 0 to 4
  
  for number in range(5, 10):
      print(number)  # 5 to 9
  
  for number in range(5, 10, 2):
      print(number)  # 5, 7, 9
  

Data Structures

Lists

• Example:

  names = ["John", "Bob", "Mosh", "Sam", "Mary"]
  print(names)
  print(names[0])  # 'John'
  print(names[-1])  # 'Mary'
  names[0] = "Jonathan"
  print(names[0:3])  # ['Jonathan', 'Bob', 'Mosh']
  

• List Methods:
  • append(), insert(), remove(), clear(), in, len()

Tuples

• Example:

  numbers = (1, 2, 3)
  

• Immutable: Cannot modify elements after creation