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Python Programming Lecture Notes

Jun 28, 2024

Python Programming Lecture Notes

Introduction

  • Purpose: Teach Python programming from basics to advanced concepts.
  • Benefits: Popular, beginner-friendly language; widely used in jobs, automation, and scripting.

Installation

  1. Python: Go to python.org to download Python 3.x (recommended) or Python 2.x (legacy, not supported in the future).
  2. Text Editor (IDE): Recommended IDE is PyCharm from JetBrains for writing Python code.

Getting Started

  • First Program: Print "Hello, World!". Scripts to draw simple shapes using print statements and use variables.
  • Hello World Example: print("Hello, World!")

Core Concepts

Variables

  • Definition: Containers for storing data values
  • Types: Strings, numbers, Booleans (true/false values)
  • Usage:
character_name = "Alice"
character_age = 50
is_adult = True

Strings

  • Creating: phrase = "Hello, World!"
  • Common Functions: lower(), upper(), isupper(), index(), replace()
  • Slicing: Accessing individual characters by index
phrase[0]  # first character
phrase[1:4]  # substring from index 1 to 3

Numbers

  • Arithmetic: Basic operations (+, -, *, /, %)
  • Functions: abs(), pow(), max(), min(), round(), sqrt() (require 'math' module)

Getting User Input

  • Input: Use input(prompt) to get data from the user
name = input("Enter your name: ")
print("Hello, " + name)

Control Flow

If Statements

  • Syntax:
if condition:
    action
elif other_condition:
    another_action
else:
    action_if_all_false
  • Boolean Logic: and, or, not

Loops

  • While Loops: Repeat block while condition is true
while condition:
    action
  • For Loops: Repeat block for each item in collection
for item in collection:
    action
for number in range(1, 11):
    print(number)
  • Break: Exit the loop
  • Continue: Skip remainder of loop and start next iteration

Functions

Definition and Call

def say_hi(name):
    print("Hello, " + name)

say_hi("Alice")

Return Statement

  • Purpose: Return data from a function
def add(a, b):
    return a + b
result = add(3, 5)  # result = 8

Advanced Concepts

  • Function Parameters: Pass multiple pieces of information to functions
  • Default Parameters: Set default values for parameters

Data Structures

Lists

  • Definition: Ordered collection of items
  • Creating: friends = ["Alice", "Bob", "Charlie"]
  • Accessing Items: Indexing friends[0]
  • Modification: Append, insert, remove, clear, pop, etc.

Tuples

  • Definition: Immutable lists
  • Creating: coordinates = (4, 5)
  • Usage: Store values that shouldn’t change

Dictionaries

  • Definition: Key-value pairs
  • Creating: { "Apples": "Red", "Bananas": "Yellow" }
  • Accessing Values: By key dict["Apples"]

Error Handling

  • Try/Except Blocks
try:
    action
except ExceptionType as e:
    handle_exception(e)

File Operations

Reading Files

  • Open File for reading: open('filename', 'r')
  • Reading Methods: read(), readline(), readlines()
file = open('employees.txt', 'r')
print(file.read())   # Read entire file

Writing Files

  • Modes: 'w' (write), 'a' (append), 'r' (read)
file = open('employees.txt', 'a')
file.write("Toby - Human Resources")
file.close()

Modules

Using Modules

  • Importing: import module_name, from module_name import *

Packages

  • External Libraries: Install using pip
pip install library_name

Classes and Objects

Basics

  • Class Definition
class Student:
    def __init__(self, name, age):
        self.name = name
        self.age = age
  • Creating Objects
student1 = Student("Alice", 20)

Methods

  • Adding Methods: Define functions inside class
class Student:
    def greet(self):
        print("Hello, " + self.name)

Inheritance

  • Deriving Subclasses
class GraduateStudent(Student):
    def __init__(self, name, age, degree):
        super().__init__(name, age)
        self.degree = degree

Miscellaneous

The Python Interpreter

  • Usage: Interactive shell for quick Python execution
python3  # Open Python interpreter

Comments

  • Single Line: # Comment
  • Multi-line: Triple quotes ''' comment '''

These notes are designed to help you recall and review the key material from the Python programming course, aiding you in your study and development as a Python programmer. Happy coding! 🐍

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