📊 Python Data Types

# Integer (int) - whole numbers
age = 25
count = -10
big_number = 1_000_000  # Underscores for readability

# Float - decimal numbers
price = 19.99
temperature = -5.5
scientific = 1.5e-4  # 0.00015

# Complex numbers
z = 3 + 4j
print(z.real)  # 3.0
print(z.imag)  # 4.0

# Type conversion
x = int(3.8)    # 3
y = float(5)    # 5.0
z = str(42)     # "42"

# Arithmetic
print(10 + 3)   # 13
print(10 - 3)   # 7
print(10 * 3)   # 30
print(10 / 3)   # 3.333...
print(10 // 3)  # 3 (floor division)
print(10 % 3)   # 1 (modulo)
print(10 ** 3)  # 1000 (power)

# String creation
name = "Alice"
message = 'Hello World'
multi_line = """This is
a multi-line
string"""

# String operations
greeting = "Hello"
full = greeting + " " + name  # Concatenation
repeat = "Ha" * 3  # "HaHaHa"

# String methods
text = "  Python Programming  "
print(text.upper())      # "  PYTHON PROGRAMMING  "
print(text.lower())      # "  python programming  "
print(text.strip())      # "Python Programming"
print(text.replace("Python", "Java"))
print(text.split())      # ['Python', 'Programming']

# String indexing & slicing
word = "Python"
print(word[0])      # 'P' (first character)
print(word[-1])     # 'n' (last character)
print(word[0:3])    # 'Pyt' (slice)
print(word[:3])     # 'Pyt'
print(word[3:])     # 'hon'
print(word[::-1])   # 'nohtyP' (reverse)

# String formatting
name = "Bob"
age = 25
print(f"{name} is {age} years old")  # f-strings (Python 3.6+)
print("{} is {} years old".format(name, age))
print("%s is %d years old" % (name, age))

# Boolean values
is_active = True
is_logged_in = False

# Boolean operations
print(True and False)   # False
print(True or False)    # True
print(not True)         # False

# Comparisons return boolean
print(5 > 3)    # True
print(5 == 5)   # True
print(5 != 3)   # True

# Truthy and Falsy values
# Falsy: False, None, 0, 0.0, "", [], {}, ()
# Everything else is Truthy
if "":
    print("This won't print")

if "Hello":
    print("This will print")

# List creation
fruits = ["apple", "banana", "cherry"]
numbers = [1, 2, 3, 4, 5]
mixed = [1, "hello", True, 3.14]

# List methods
fruits.append("orange")     # Add to end
fruits.insert(1, "mango")   # Insert at index
fruits.remove("banana")     # Remove by value
popped = fruits.pop()       # Remove and return last
fruits.sort()               # Sort in place
fruits.reverse()            # Reverse in place

# List operations
print(len(fruits))          # Length
print(fruits[0])            # First item
print(fruits[-1])           # Last item
print(fruits[1:3])          # Slice
print("apple" in fruits)    # Check membership

# List comprehension
squares = [x**2 for x in range(5)]  # [0, 1, 4, 9, 16]
evens = [x for x in range(10) if x % 2 == 0]  # [0, 2, 4, 6, 8]

# Tuple creation
coordinates = (10, 20)
rgb = (255, 0, 128)
single = (42,)  # Single element tuple needs comma

# Tuple unpacking
x, y = coordinates
print(x)  # 10

# Tuples are immutable
# coordinates[0] = 15  # Error!

# Use tuples for fixed data
point = (3, 4)
person = ("Alice", 30, "Engineer")

# Dictionary creation
person = {
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

# Accessing values
print(person["name"])           # "Alice"
print(person.get("age"))        # 30
print(person.get("job", "N/A")) # Default if key doesn't exist

# Modifying
person["age"] = 31              # Update
person["job"] = "Engineer"      # Add new key

# Dictionary methods
print(person.keys())            # All keys
print(person.values())          # All values
print(person.items())           # Key-value pairs

# Loop through dictionary
for key, value in person.items():
    print(f"{key}: {value}")

# Dictionary comprehension
squares = {x: x**2 for x in range(5)}  # {0: 0, 1: 1, 2: 4, ...}

# Set creation
numbers = {1, 2, 3, 3, 4}  # {1, 2, 3, 4} - duplicates removed
fruits = set(["apple", "banana", "apple"])  # {'apple', 'banana'}

# Set operations
numbers.add(5)              # Add element
numbers.remove(3)           # Remove element
numbers.discard(10)         # Remove if exists (no error)

# Set math
a = {1, 2, 3, 4}
b = {3, 4, 5, 6}
print(a | b)  # Union: {1, 2, 3, 4, 5, 6}
print(a & b)  # Intersection: {3, 4}
print(a - b)  # Difference: {1, 2}
print(a ^ b)  # Symmetric difference: {1, 2, 5, 6}

# None represents absence of value
result = None

# Check for None
if result is None:
    print("No result yet")

# Functions return None by default
def do_nothing():
    pass

value = do_nothing()
print(value)  # None