Complete Python Course

# This is a comment print("Hello, World!") print("Welcome to Python!") # Variables name = "Alice" age = 25 print(f"My name is {name} and I'm {age} years old")

# Variable assignment x = 10 y = 20 z = x + y # Multiple assignment a, b, c = 1, 2, 3 # Swapping variables x, y = y, x # Constants (by convention, use UPPERCASE) PI = 3.14159 MAX_SIZE = 100

# Numbers integer = 42 float_num = 3.14 complex_num = 2 + 3j # Strings single_quote = 'Hello' double_quote = "World" multiline = """This is a multiline string""" # Boolean is_true = True is_false = False # None (null value) nothing = None # Check type print(type(integer)) # print(type(float_num)) #

name = "Python" # String methods print(name.upper()) # PYTHON print(name.lower()) # python print(name.capitalize()) # Python print(len(name)) # 6 # String formatting age = 25 message = f"I am {age} years old" # f-strings (Python 3.6+) message2 = "I am {} years old".format(age) # .format() message3 = "I am %d years old" % age # % formatting # String slicing text = "Hello, World!" print(text[0]) # H print(text[7:12]) # World print(text[:5]) # Hello print(text[7:]) # World! print(text[-1]) # !

# Creating lists fruits = ["apple", "banana", "orange"] numbers = [1, 2, 3, 4, 5] mixed = [1, "hello", 3.14, True] # List operations fruits.append("grape") # Add to end fruits.insert(1, "mango") # Insert at index fruits.remove("banana") # Remove by value popped = fruits.pop() # Remove and return last item # List slicing print(numbers[1:4]) # [2, 3, 4] print(numbers[:3]) # [1, 2, 3] print(numbers[2:]) # [3, 4, 5] # List comprehension squares = [x**2 for x in range(1, 6)] # [1, 4, 9, 16, 25] evens = [x for x in range(10) if x % 2 == 0] # [0, 2, 4, 6, 8]

# Creating dictionaries person = { "name": "Alice", "age": 30, "city": "New York" } # Accessing values print(person["name"]) # Alice print(person.get("age")) # 30 print(person.get("country", "Unknown")) # Unknown (default) # Modifying dictionaries person["age"] = 31 # Update value person["country"] = "USA" # Add new key-value pair del person["city"] # Delete key-value pair # Dictionary methods print(person.keys()) # dict_keys(['name', 'age', 'country']) print(person.values()) # dict_values(['Alice', 31, 'USA']) print(person.items()) # dict_items([('name', 'Alice'), ...])

# Tuples (immutable) coordinates = (10, 20) rgb = (255, 128, 0) single_item = (42,) # Note the comma # Tuple unpacking x, y = coordinates r, g, b = rgb # Sets (unique elements) numbers = {1, 2, 3, 4, 5} unique_letters = set("hello") # {'h', 'e', 'l', 'o'} # Set operations set1 = {1, 2, 3} set2 = {3, 4, 5} print(set1 | set2) # Union: {1, 2, 3, 4, 5} print(set1 & set2) # Intersection: {3} print(set1 - set2) # Difference: {1, 2}

# If statements age = 18 if age >= 18: print("You are an adult") elif age >= 13: print("You are a teenager") else: print("You are a child") # Ternary operator status = "adult" if age >= 18 else "minor" # Multiple conditions score = 85 if score >= 90 and score <= 100: grade = "A" elif score >= 80: grade = "B" elif score >= 70: grade = "C" else: grade = "F"

# For loops fruits = ["apple", "banana", "orange"] # Iterate over list for fruit in fruits: print(fruit) # Iterate with index for i, fruit in enumerate(fruits): print(f"{i}: {fruit}") # Range function for i in range(5): # 0, 1, 2, 3, 4 print(i) for i in range(1, 6): # 1, 2, 3, 4, 5 print(i) for i in range(0, 10, 2): # 0, 2, 4, 6, 8 print(i) # While loops count = 0 while count < 5: print(f"Count: {count}") count += 1 # Loop control for i in range(10): if i == 3: continue # Skip this iteration if i == 7: break # Exit loop print(i)

# Try-except blocks try: number = int(input("Enter a number: ")) result = 10 / number print(f"Result: {result}") except ValueError: print("Invalid input! Please enter a number.") except ZeroDivisionError: print("Cannot divide by zero!") except Exception as e: print(f"An error occurred: {e}") else: print("No errors occurred!") finally: print("This always executes") # Raising exceptions def validate_age(age): if age < 0: raise ValueError("Age cannot be negative") if age > 150: raise ValueError("Age seems unrealistic") return True

# Basic function def greet(name): return f"Hello, {name}!" # Function with default parameters def greet_with_title(name, title="Mr."): return f"Hello, {title} {name}!" # Function with multiple parameters def calculate_area(length, width): return length * width # Function with variable arguments def sum_all(*args): return sum(args) # Function with keyword arguments def create_profile(**kwargs): profile = {} for key, value in kwargs.items(): profile[key] = value return profile # Using functions print(greet("Alice")) # Hello, Alice! print(greet_with_title("Bob", "Dr.")) # Hello, Dr. Bob! print(calculate_area(5, 3)) # 15 print(sum_all(1, 2, 3, 4, 5)) # 15 print(create_profile(name="Alice", age=30)) # {'name': 'Alice', 'age': 30}

# Lambda (anonymous) functions square = lambda x: x ** 2 add = lambda x, y: x + y print(square(5)) # 25 print(add(3, 4)) # 7 # Using lambda with built-in functions numbers = [1, 2, 3, 4, 5] squared = list(map(lambda x: x**2, numbers)) # [1, 4, 9, 16, 25] evens = list(filter(lambda x: x % 2 == 0, numbers)) # [2, 4] # Sorting with lambda students = [("Alice", 85), ("Bob", 90), ("Charlie", 78)] students.sort(key=lambda x: x[1]) # Sort by grade print(students) # [('Charlie', 78), ('Alice', 85), ('Bob', 90)]

# Simple decorator def my_decorator(func): def wrapper(): print("Before function call") func() print("After function call") return wrapper @my_decorator def say_hello(): print("Hello!") say_hello() # Output: # Before function call # Hello! # After function call # Decorator with arguments def timer(func): import time def wrapper(*args, **kwargs): start = time.time() result = func(*args, **kwargs) end = time.time() print(f"{func.__name__} took {end - start:.4f} seconds") return result return wrapper @timer def slow_function(): import time time.sleep(1) return "Done!"

# Basic class class Person: # Class variable species = "Homo sapiens" # Constructor def __init__(self, name, age): self.name = name # Instance variable self.age = age # Instance variable # Instance method def introduce(self): return f"Hi, I'm {self.name} and I'm {self.age} years old" # Instance method def have_birthday(self): self.age += 1 return f"Happy birthday! {self.name} is now {self.age}" # Class method @classmethod def get_species(cls): return cls.species # Static method @staticmethod def is_adult(age): return age >= 18 # Creating objects person1 = Person("Alice", 25) person2 = Person("Bob", 17) print(person1.introduce()) # Hi, I'm Alice and I'm 25 years old print(person1.have_birthday()) # Happy birthday! Alice is now 26 print(Person.is_adult(person2.age)) # False

# Parent class class Animal: def __init__(self, name, species): self.name = name self.species = species def make_sound(self): return "Some generic animal sound" def info(self): return f"{self.name} is a {self.species}" # Child class class Dog(Animal): def __init__(self, name, breed): super().__init__(name, "Dog") # Call parent constructor self.breed = breed def make_sound(self): # Override parent method return "Woof!" def fetch(self): return f"{self.name} is fetching the ball!" class Cat(Animal): def __init__(self, name, color): super().__init__(name, "Cat") self.color = color def make_sound(self): return "Meow!" def climb(self): return f"{self.name} is climbing a tree!" # Using inheritance dog = Dog("Buddy", "Golden Retriever") cat = Cat("Whiskers", "Orange") print(dog.info()) # Buddy is a Dog print(dog.make_sound()) # Woof! print(dog.fetch()) # Buddy is fetching the ball! print(cat.info()) # Whiskers is a Cat print(cat.make_sound()) # Meow! print(cat.climb()) # Whiskers is climbing a tree!

class BankAccount: def __init__(self, account_number, initial_balance=0): self.account_number = account_number self._balance = initial_balance # Protected attribute self.__pin = None # Private attribute @property def balance(self): return self._balance @balance.setter def balance(self, amount): if amount < 0: raise ValueError("Balance cannot be negative") self._balance = amount def deposit(self, amount): if amount > 0: self._balance += amount return f"Deposited ${amount}. New balance: ${self._balance}" return "Invalid deposit amount" def withdraw(self, amount): if 0 < amount <= self._balance: self._balance -= amount return f"Withdrew ${amount}. New balance: ${self._balance}" return "Insufficient funds or invalid amount" def set_pin(self, pin): if len(str(pin)) == 4: self.__pin = pin return "PIN set successfully" return "PIN must be 4 digits" # Using the class account = BankAccount("123456789", 1000) print(account.deposit(500)) # Deposited $500. New balance: $1500 print(account.withdraw(200)) # Withdrew $200. New balance: $1300 print(account.balance) # 1300

# Different ways to import import math import random as rand from datetime import datetime, timedelta from collections import * # Using imported modules print(math.pi) # 3.141592653589793 print(math.sqrt(16)) # 4.0 print(rand.randint(1, 10)) # Random number between 1 and 10 # Date and time now = datetime.now() tomorrow = now + timedelta(days=1) print(f"Today: {now.strftime('%Y-%m-%d')}") print(f"Tomorrow: {tomorrow.strftime('%Y-%m-%d')}") # Collections counter = Counter("hello world") print(counter) # Counter({'l': 3, 'o': 2, 'h': 1, 'e': 1, ' ': 1, 'w': 1, 'r': 1, 'd': 1})

# File: my_math.py def add(a, b): """Add two numbers""" return a + b def multiply(a, b): """Multiply two numbers""" return a * b def factorial(n): """Calculate factorial of n""" if n <= 1: return 1 return n * factorial(n - 1) PI = 3.14159 # File: main.py import my_math result = my_math.add(5, 3) print(f"5 + 3 = {result}") fact = my_math.factorial(5) print(f"5! = {fact}") print(f"PI = {my_math.PI}")

# Writing to a file with open("example.txt", "w") as file: file.write("Hello, World!\n") file.write("This is a test file.\n") # Reading from a file with open("example.txt", "r") as file: content = file.read() print(content) # Reading line by line with open("example.txt", "r") as file: for line in file: print(line.strip()) # strip() removes newline characters # Appending to a file with open("example.txt", "a") as file: file.write("This line is appended.\n") # Reading all lines into a list with open("example.txt", "r") as file: lines = file.readlines() print(lines)

import csv # Writing CSV data = [ ["Name", "Age", "City"], ["Alice", 25, "New York"], ["Bob", 30, "Los Angeles"], ["Charlie", 35, "Chicago"] ] with open("people.csv", "w", newline="") as file: writer = csv.writer(file) writer.writerows(data) # Reading CSV with open("people.csv", "r") as file: reader = csv.reader(file) for row in reader: print(row) # Using DictReader for named columns with open("people.csv", "r") as file: reader = csv.DictReader(file) for row in reader: print(f"{row['Name']} is {row['Age']} years old")

import json # Python dictionary person = { "name": "Alice", "age": 30, "city": "New York", "hobbies": ["reading", "swimming", "coding"] } # Writing JSON to file with open("person.json", "w") as file: json.dump(person, file, indent=2) # Reading JSON from file with open("person.json", "r") as file: loaded_person = json.load(file) print(loaded_person) # Converting to/from JSON strings json_string = json.dumps(person, indent=2) print(json_string) parsed_data = json.loads(json_string) print(parsed_data["name"]) # Alice

import requests # GET request response = requests.get("https://api.github.com/users/octocat") if response.status_code == 200: data = response.json() print(f"User: {data['name']}") print(f"Public repos: {data['public_repos']}") # POST request data = {"name": "John", "email": "john@example.com"} response = requests.post("https://httpbin.org/post", json=data) print(response.json()) # With headers headers = {"Authorization": "Bearer your-token"} response = requests.get("https://api.example.com/data", headers=headers)

import pandas as pd # Creating a DataFrame data = { "Name": ["Alice", "Bob", "Charlie", "Diana"], "Age": [25, 30, 35, 28], "City": ["New York", "Los Angeles", "Chicago", "Houston"], "Salary": [50000, 60000, 70000, 55000] } df = pd.DataFrame(data) print(df) # Basic operations print(df.head()) # First 5 rows print(df.describe()) # Statistical summary print(df["Age"].mean()) # Average age print(df[df["Age"] > 30]) # Filter rows # Reading from CSV # df = pd.read_csv("data.csv") # Grouping and aggregation grouped = df.groupby("City")["Salary"].mean() print(grouped)

import matplotlib.pyplot as plt import numpy as np # Simple line plot x = np.linspace(0, 10, 100) y = np.sin(x) plt.figure(figsize=(10, 6)) plt.plot(x, y, label="sin(x)") plt.xlabel("x") plt.ylabel("y") plt.title("Sine Wave") plt.legend() plt.grid(True) plt.show() # Bar chart categories = ["A", "B", "C", "D"] values = [23, 45, 56, 78] plt.figure(figsize=(8, 6)) plt.bar(categories, values, color=["red", "green", "blue", "orange"]) plt.title("Bar Chart Example") plt.xlabel("Categories") plt.ylabel("Values") plt.show() # Scatter plot x = np.random.randn(100) y = np.random.randn(100) plt.figure(figsize=(8, 6)) plt.scatter(x, y, alpha=0.6) plt.title("Scatter Plot") plt.xlabel("X values") plt.ylabel("Y values") plt.show()

class TodoList: def __init__(self): self.tasks = [] def add_task(self, task): self.tasks.append({"task": task, "completed": False}) print(f"Added: {task}") def complete_task(self, index): if 0 <= index < len(self.tasks): self.tasks[index]["completed"] = True print(f"Completed: {self.tasks[index]['task']}") else: print("Invalid task index") def remove_task(self, index): if 0 <= index < len(self.tasks): removed = self.tasks.pop(index) print(f"Removed: {removed['task']}") else: print("Invalid task index") def show_tasks(self): if not self.tasks: print("No tasks in the list") return for i, task in enumerate(self.tasks): status = "✓" if task["completed"] else "○" print(f"{i + 1}. {status} {task['task']}") # Usage todo = TodoList() todo.add_task("Learn Python") todo.add_task("Build a project") todo.add_task("Practice coding") todo.show_tasks() todo.complete_task(0) todo.show_tasks()

class Calculator: def add(self, a, b): return a + b def subtract(self, a, b): return a - b def multiply(self, a, b): return a * b def divide(self, a, b): if b == 0: return "Error: Division by zero" return a / b def power(self, a, b): return a ** b def sqrt(self, a): if a < 0: return "Error: Cannot calculate square root of negative number" return a ** 0.5 def calculator_app(): calc = Calculator() while True: print("\n--- Calculator ---") print("1. Add") print("2. Subtract") print("3. Multiply") print("4. Divide") print("5. Power") print("6. Square Root") print("7. Exit") choice = input("Choose operation (1-7): ") if choice == "7": print("Goodbye!") break if choice in ["1", "2", "3", "4", "5"]: try: a = float(input("Enter first number: ")) b = float(input("Enter second number: ")) if choice == "1": result = calc.add(a, b) elif choice == "2": result = calc.subtract(a, b) elif choice == "3": result = calc.multiply(a, b) elif choice == "4": result = calc.divide(a, b) elif choice == "5": result = calc.power(a, b) print(f"Result: {result}") except ValueError: print("Invalid input! Please enter numbers only.") elif choice == "6": try: a = float(input("Enter number: ")) result = calc.sqrt(a) print(f"Result: {result}") except ValueError: print("Invalid input! Please enter a number.") else: print("Invalid choice! Please try again.") # Uncomment to run # calculator_app()