Python for Beginners
Start Your Coding Journey

print("Hello, World!")

age = 25
print("Age:", age)
print("Type of age:", type(age))

price = 19.99
print("Price:", price)
print("Type of price:", type(price))

name = "Alice"
print("Name:", name)
print("Type of name:", type(name))

is_student = True
print("Is student:", is_student)
print("Type of is_student:", type(is_student))

age = "twenty-five"
print("Age now:", age)
print("Type now:", type(age))

greeting = "Hello"
name = "World"
message = greeting + " " + name + "!"
print("Message:", message)

word = "Python"
print("First character:", word[0])
print("Last character:", word[-1])
print("Slice (0:3):", word[0:3])

text = "  Hello, World!  "
print("Original:", text)
print("Upper:", text.upper())
print("Lower:", text.lower())
print("Strip:", text.strip())
print("Title:", text.strip().title())
print("Replace:", text.replace("World", "Python"))
print("Length:", len(text))

a = 10
b = 3

print("a + b =", a + b)
print("a - b =", a - b)
print("a * b =", a * b)
print("a / b =", a / b)
print("a // b =", a // b)
print("a % b =", a % b)
print("a ** b =", a ** b)

result = 2 + 3 * 4 ** 2
print("2 + 3 * 4 ** 2 =", result)

result2 = (2 + 3) * (4 ** 2)
print("(2 + 3) * (4 ** 2) =", result2)

x = 5
y = 2.5
print("x + y =", x + y)
print("int(2.9) =", int(2.9))
print("float(5) =", float(5))

fruits = ["apple", "banana", "orange", "grape"]
print("Fruits:", fruits)

print("First fruit:", fruits[0])
print("Last fruit:", fruits[-1])
print("First two:", fruits[0:2])

fruits[1] = "blueberry"
print("After modification:", fruits)

fruits.append("kiwi")
print("After append:", fruits)
fruits.insert(1, "mango")
print("After insert:", fruits)

fruits.remove("orange")
print("After remove:", fruits)
last = fruits.pop()
print("Popped:", last)
print("After pop:", fruits)

numbers = [3, 1, 4, 1, 5, 9, 2]
numbers.sort()
print("Sorted:", numbers)
numbers.reverse()
print("Reversed:", numbers)
print("Count of 1:", numbers.count(1))
print("Index of 5:", numbers.index(5))

coordinates = (10, 20)
rgb = (255, 128, 0)
person = ("Alice", 25, "Engineer")
print("Coordinates:", coordinates)
print("RGB:", rgb)
print("Person:", person)

print("X:", coordinates[0])
print("Y:", coordinates[1])
print("First color:", rgb[0])

x, y = coordinates
print("Unpacked x:", x)
print("Unpacked y:", y)

name, age, job = person
print("Name:", name)
print("Age:", age)
print("Job:", job)

single = (42,)
print("Single element tuple:", single)

def get_stats(numbers):
    return min(numbers), max(numbers), sum(numbers)/len(numbers)

min_val, max_val, avg = get_stats([5, 10, 15, 20])
print("Min:", min_val, "Max:", max_val, "Average:", avg)

person = {
    "name": "Alice",
    "age": 30,
    "city": "New York",
    "job": "Engineer"
}
print("Person:", person)

print("Name:", person["name"])
print("Age:", person["age"])

print("Country:", person.get("country", "Unknown"))

person["country"] = "USA"
person["age"] = 31
print("Updated:", person)

print("Keys:", person.keys())
print("Values:", person.values())
print("Items:", person.items())

print("\nIterating over items:")
for key, value in person.items():
    print(f"{key}: {value}")

squares = {x: x**2 for x in range(5)}
print("Squares:", squares)

users = {
    "alice": {"age": 30, "city": "NYC"},
    "bob": {"age": 25, "city": "LA"}
}
print("Alice's city:", users["alice"]["city"])

fruits = {"apple", "banana", "orange", "apple", "banana"}
print("Fruits (duplicates removed):", fruits)

numbers = [1, 2, 3, 2, 1, 4, 5]
unique = set(numbers)
print("Unique numbers:", unique)

fruits.add("grape")
print("After add:", fruits)
fruits.remove("banana")
print("After remove:", fruits)

set_a = {1, 2, 3, 4, 5}
set_b = {4, 5, 6, 7, 8}

print("Union:", set_a | set_b)
print("Intersection:", set_a & set_b)
print("Difference (A - B):", set_a - set_b)
print("Symmetric difference:", set_a ^ set_b)

print("Is 3 in set_a?", 3 in set_a)
print("Is 10 in set_a?", 10 in set_a)

squares = {x**2 for x in range(6)}
print("Squares set:", squares)

age = 20
if age >= 18:
    print("You are an adult")
else:
    print("You are a minor")

score = 85
if score >= 90:
    grade = "A"
elif score >= 80:
    grade = "B"
elif score >= 70:
    grade = "C"
elif score >= 60:
    grade = "D"
else:
    grade = "F"
print("Grade:", grade)

temperature = 25
is_sunny = True
if temperature > 30:
    print("It's hot")
elif temperature > 20 and is_sunny:
    print("It's warm and sunny")
elif temperature > 20:
    print("It's warm")
else:
    print("It's cool")

x = 10
if x > 0:
    if x % 2 == 0:
        print("x is positive and even")
    else:
        print("x is positive and odd")
else:
    print("x is not positive")

age = 16
status = "Adult" if age >= 18 else "Minor"
print("Status:", status)

fruits = ["apple", "banana", "orange"]
for fruit in fruits:
    print("I like", fruit)

print("\nCounting with range:")
for i in range(5):
    print(i, end=" ")
print()

print("\nWith index:")
for i, fruit in enumerate(fruits):
    print(f"{i}: {fruit}")

print("\nWhile loop:")
count = 0
while count < 5:
    print(count, end=" ")
    count += 1
print()

print("\nBreak and continue:")
for i in range(10):
    if i == 3:
        continue
    if i == 7:
        break
    print(i, end=" ")
print()

person = {"name": "Alice", "age": 30, "city": "NYC"}
print("\nDictionary loop:")
for key, value in person.items():
    print(f"{key}: {value}")

print("\nNested loops:")
for i in range(3):
    for j in range(2):
        print(f"({i},{j})", end=" ")
    print()

def greet(name):
    return f"Hello, {name}!"

print(greet("Alice"))
print(greet("Bob"))

def add(a, b):
    return a + b

result = add(5, 3)
print("5 + 3 =", result)

def power(base, exponent=2):
    return base ** exponent

print("3^2 =", power(3))
print("2^3 =", power(2, 3))

def sum_all(*numbers):
    return sum(numbers)

print("Sum of 1, 2, 3:", sum_all(1, 2, 3))
print("Sum of 1, 2, 3, 4, 5:", sum_all(1, 2, 3, 4, 5))

def describe_person(name, age, city="Unknown"):
    return f"{name} is {age} years old and lives in {city}"

print(describe_person("Alice", 30, "NYC"))
print(describe_person("Bob", 25))

square = lambda x: x ** 2
print("Lambda square of 5:", square(5))

def apply(func, value):
    return func(value)

print("apply(square, 4):", apply(square, 4))

try:
    number = int(input("Enter a number: "))
    print("You entered:", number)
except ValueError:
    print("That's not a valid number!")

try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero!")
except TypeError:
    print("Invalid type for division!")
except Exception as e:
    print("Something went wrong:", e)

try:
    file = open("example.txt", "r")
    content = file.read()
except FileNotFoundError:
    print("File not found!")
else:
    print("File content length:", len(content))
finally:
    try:
        file.close()
    except:
        pass
    print("Cleanup complete.")

def validate_age(age):
    if age < 0:
        raise ValueError("Age cannot be negative")
    elif age > 150:
        raise ValueError("Age cannot be greater than 150")
    return f"Valid age: {age}"

try:
    print(validate_age(25))
    print(validate_age(-5))
except ValueError as e:
    print("Error:", e)

import math
print("math.pi =", math.pi)
print("math.sqrt(16) =", math.sqrt(16))
print("math.factorial(5) =", math.factorial(5))

from math import sin, cos, radians
angle = radians(45)
print("sin(45°) =", sin(angle))
print("cos(45°) =", cos(angle))

import random as rnd
print("Random integer (1-10):", rnd.randint(1, 10))
print("Random choice:", rnd.choice(["apple", "banana", "orange"]))

from datetime import datetime
now = datetime.now()
print("Current date and time:", now)
print("Year:", now.year)
print("Month:", now.month)

try:
    import pandas as pd
    print("Pandas is installed! Version:", pd.__version__)
except ImportError:
    print("Pandas is not installed. Run: pip install pandas")

with open("example.txt", "w") as file:
    file.write("Hello, World!\n")
    file.write("This is line 2.\n")
    file.write("This is line 3.\n")
print("File written successfully.")

with open("example.txt", "r") as file:
    content = file.read()
print("File content:")
print(content)

print("Reading line by line:")
with open("example.txt", "r") as file:
    for line in file:
        print(f"Line: {line.strip()}")

with open("example.txt", "r") as file:
    lines = file.readlines()
print("Lines list:", lines)

with open("example.txt", "a") as file:
    file.write("This line was appended.\n")
print("Appended successfully.")

fruits = ["apple\n", "banana\n", "orange\n"]
with open("fruits.txt", "w") as file:
    file.writelines(fruits)

try:
    with open("nonexistent.txt", "r") as file:
        content = file.read()
except FileNotFoundError:
    print("File not found!")

data = [
    ["Alice", "30", "Engineer"],
    ["Bob", "25", "Designer"],
    ["Charlie", "35", "Manager"]
]
with open("people.csv", "w") as file:
    for row in data:
        file.write(",".join(row) + "\n")
print("CSV written.")

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def greet(self):
        return f"Hello, my name is {self.name} and I am {self.age} years old."

    def birthday(self):
        self.age += 1
        print(f"{self.name} is now {self.age} years old!")

alice = Person("Alice", 30)
bob = Person("Bob", 25)

print(alice.greet())
print(bob.greet())

alice.birthday()
bob.birthday()

class Student:
    school = "Python University"

    def __init__(self, name, grade):
        self.name = name
        self.grade = grade

    def display(self):
        return f"{self.name} (Grade: {self.grade}) at {Student.school}"

s1 = Student("Alice", "A")
s2 = Student("Bob", "B")
print(s1.display())
print(s2.display())

class Animal:
    def __init__(self, name):
        self.name = name

    def speak(self):
        return "Some sound"

class Dog(Animal):
    def speak(self):
        return "Woof!"

class Cat(Animal):
    def speak(self):
        return "Meow!"

dog = Dog("Rex")
cat = Cat("Whiskers")
print(f"{dog.name} says: {dog.speak()}")
print(f"{cat.name} says: {cat.speak()}")

class Rectangle:
    def __init__(self, width, height):
        self._width = width
        self._height = height

    @property
    def area(self):
        return self._width * self._height

    @property
    def perimeter(self):
        return 2 * (self._width + self._height)

rect = Rectangle(4, 5)
print(f"Area: {rect.area}")
print(f"Perimeter: {rect.perimeter}")