Conditional Statements

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CONDITIONAL STATEMENTS - IF/ELIF/ELSE
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print("--- Understanding Conditional Statements ---")
print("Conditional statements control program flow based on True/False conditions")
print("Three main types: if, elif, else")
When to use them together - mutually exclusive conditions
print("\n--- When to Use if/elif/else Together ---")
def check_grade(score):
"""Demonstrate mutually exclusive conditions."""
if score >= 90:
return "A"
elif score >= 80:
return "B"
elif score >= 70:
return "C"
elif score >= 60:
return "D"
else:
return "F"
Test the grading function
test_scores = [95, 87, 72, 65, 45]
print("Grade checking (mutually exclusive conditions):")
for score in test_scores:
grade = check_grade(score)
print(f"  Score {score} -> Grade {grade}")
print("\nWhy if/elif/else together?")
print("  - Only ONE condition block executes")
print("  - Conditions are checked in order")
print("  - First True condition wins")
print("  - 'else' catches everything that doesn't match")
When to use discrete if statements - independent conditions
print("\n--- When to Use Discrete 'if' Statements ---")
def check_weather_conditions(temperature, weather, humidity):
"""Demonstrate independent conditions that can all be true."""
messages = []
if temperature > 80:
    messages.append("It's hot outside!")

if weather == "sunny":
    messages.append("Don't forget sunscreen!")

if humidity > 70:
    messages.append("It's quite humid today.")

if temperature > 85 and weather == "sunny":
    messages.append("Perfect beach weather!")

return messages
Test independent conditions
print("Weather condition checking (independent conditions):")
conditions = [
(85, "sunny", 75),
(70, "cloudy", 60),
(90, "sunny", 80)
]
for temp, weather, humid in conditions:
messages = check_weather_conditions(temp, weather, humid)
print(f"  Temp: {temp}°F, Weather: {weather}, Humidity: {humid}%")
for msg in messages:
print(f"    -> {msg}")
print("\nWhy discrete if statements?")
print("  - Multiple conditions can be True simultaneously")
print("  - Each condition is evaluated independently")
print("  - All matching conditions execute")
=============================================================================
FOR LOOPS WITH RANGE FUNCTION
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print("\n" + "="*60)
print("FOR LOOPS WITH RANGE FUNCTION")
print("="*60)
Understanding Start/Stop/Step parameters
print("--- Understanding range(start, stop, step) ---")
print("range() function signature: range(start=0, stop, step=1)")
print("  - start: where to begin (default: 0)")
print("  - stop: where to end (exclusive - not included)")
print("  - step: increment amount (default: 1)")
def demonstrate_range_parameters():
"""Show different range() parameter combinations."""
print("\nrange() parameter examples:")
# Basic range (stop only)
print("range(5) - stop only:")
for i in range(5):
    print(f"  {i}", end=" ")
print("  # Prints 0 through 4")

# Start and stop
print("\nrange(2, 8) - start and stop:")
for i in range(2, 8):
    print(f"  {i}", end=" ")
print("  # Prints 2 through 7")

# Start, stop, and step
print("\nrange(1, 10, 2) - start, stop, step:")
for i in range(1, 10, 2):
    print(f"  {i}", end=" ")
print("  # Prints 1, 3, 5, 7, 9")

# Negative step (counting backwards)
print("\nrange(10, 0, -1) - counting backwards:")
for i in range(10, 0, -1):
    print(f"  {i}", end=" ")
print("  # Prints 10 down to 1")

# Step by larger amounts
print("\nrange(0, 100, 25) - larger steps:")
for i in range(0, 100, 25):
    print(f"  {i}", end=" ")
print("  # Prints 0, 25, 50, 75")
demonstrate_range_parameters()
When to use range() - practical examples
print("\n--- When to Use range() ---")
def repeat_action_examples():
"""Show when to use range() for repetition."""
# Repeat an action N times
print("Repeating an action 3 times:")
for i in range(3):
    print(f"  Action {i+1}: Hello World!")

# Create number sequences
print("\nCreating a sequence of even numbers:")
even_numbers = []
for i in range(0, 20, 2):
    even_numbers.append(i)
print(f"  Even numbers: {even_numbers}")

# Access list items by index
print("\nAccessing list items by index:")
fruits = ["apple", "banana", "orange", "grape", "kiwi"]
for i in range(len(fruits)):
    print(f"  Index {i}: {fruits[i]}")

# Countdown timer simulation
print("\nCountdown timer:")
for i in range(5, 0, -1):
    print(f"  {i}...")
print("  Blast off!")
repeat_action_examples()
How to use range() effectively
print("\n--- How to Use range() Effectively ---")
def range_best_practices():
"""Demonstrate best practices with range()."""
# Processing chunks of data
data = list(range(1, 21))  # Numbers 1-20
chunk_size = 5

print(f"Processing data in chunks of {chunk_size}:")
for i in range(0, len(data), chunk_size):
    chunk = data[i:i+chunk_size]
    print(f"  Chunk starting at index {i}: {chunk}")

# Creating multiplication table
print("\nMultiplication table (5x5):")
for i in range(1, 6):
    row = []
    for j in range(1, 6):
        row.append(i * j)
    print(f"  {i}: {row}")

# Nested ranges for coordinates
print("\nGrid coordinates (3x3):")
for x in range(3):
    for y in range(3):
        print(f"  ({x}, {y})", end=" ")
    print()  # New line after each row
range_best_practices()
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FOR LOOPS WITH ITERABLES
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print("\n" + "="*60)
print("FOR LOOPS WITH ITERABLES")
print("="*60)
What is an iterable?
print("--- What is an Iterable? ---")
print("An iterable is any object that can be looped through one item at a time")
print("You can use a for loop to go through each element")
print("Common iterables: lists, strings, tuples, dictionaries, sets, files")
Five iterable data types with examples
print("\n--- Five Iterable Data Types ---")
def demonstrate_iterables():
"""Show examples of different iterable types."""
# 1. Lists
print("1. LISTS - Ordered, mutable collections")
colors = ["red", "green", "blue", "yellow"]
print(f"   List: {colors}")
print("   Iterating through list:")
for color in colors:
    print(f"     I like the color {color}")

# 2. Strings
print("\n2. STRINGS - Sequences of characters")
word = "Python"
print(f"   String: '{word}'")
print("   Iterating through string:")
for letter in word:
    print(f"     Letter: {letter}")

# 3. Tuples
print("\n3. TUPLES - Ordered, immutable collections")
coordinates = (10, 20, 30)
print(f"   Tuple: {coordinates}")
print("   Iterating through tuple:")
for coord in coordinates:
    print(f"     Coordinate: {coord}")

# 4. Dictionaries
print("\n4. DICTIONARIES - Key-value pairs")
student_grades = {"Alice": 95, "Bob": 87, "Charlie": 92}
print(f"   Dictionary: {student_grades}")
print("   Iterating through dictionary keys:")
for name in student_grades:
    print(f"     {name}: {student_grades[name]}")

print("   Iterating through key-value pairs:")
for name, grade in student_grades.items():
    print(f"     Student {name} scored {grade}")

# 5. Sets
print("\n5. SETS - Unordered collections of unique items")
unique_numbers = {1, 2, 3, 4, 5, 2, 3}  # Duplicates automatically removed
print(f"   Set: {unique_numbers}")
print("   Iterating through set:")
for number in unique_numbers:
    print(f"     Number: {number}")
demonstrate_iterables()
Advanced iterable examples
print("\n--- Advanced Iterable Examples ---")
def advanced_iterable_usage():
"""Show more complex iterable usage patterns."""
# Nested lists
print("Nested lists (2D data):")
matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
for row in matrix:
    print(f"  Row: {row}")
    for item in row:
        print(f"    Item: {item}")

# List of dictionaries
print("\nList of dictionaries (common data structure):")
students = [
    {"name": "Alice", "age": 20, "major": "CS"},
    {"name": "Bob", "age": 21, "major": "Math"},
    {"name": "Charlie", "age": 19, "major": "Physics"}
]

for student in students:
    print(f"  Student: {student['name']}")
    print(f"    Age: {student['age']}, Major: {student['major']}")

# String methods creating iterables
print("\nString methods that create iterables:")
sentence = "Python is awesome"
words = sentence.split()  # Creates a list
print(f"  Original: '{sentence}'")
print(f"  Words: {words}")
for word in words:
    print(f"    Word: '{word}' (length: {len(word)})")
advanced_iterable_usage()
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WHILE LOOPS FOR DATA STATE CHANGES
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print("\n" + "="*60)
print("WHILE LOOPS FOR DATA STATE CHANGES")
print("="*60)
Reducing a value to a point
print("--- Reducing a Value to a Point ---")
def demonstrate_value_reduction():
"""Show examples of reducing values with while loops."""
# Countdown example
print("Countdown example:")
countdown = 10
while countdown > 0:
    print(f"  Countdown: {countdown}")
    countdown -= 1
print("  Blast off!")

# Division until small enough
print("\nDividing number until it's less than 1:")
number = 1000
divisions = 0
while number >= 1:
    print(f"  Step {divisions}: {number}")
    number = number / 2
    divisions += 1
print(f"  Final result: {number:.6f} after {divisions} divisions")

# Removing items from a list
print("\nRemoving items from list until empty:")
items = ["apple", "banana", "cherry", "date"]
while items:  # While list is not empty
    removed = items.pop()
    print(f"  Removed '{removed}', remaining: {items}")
print("  List is now empty!")

# Factorial calculation (reducing multiplier)
print("\nFactorial calculation (5!):")
n = 5
result = 1
original_n = n
while n > 0:
    print(f"  {result} × {n} = {result * n}")
    result *= n
    n -= 1
print(f"  Final result: {original_n}! = {result}")
demonstrate_value_reduction()
Increasing a value to a point
print("\n--- Increasing a Value to a Point ---")
def demonstrate_value_increase():
"""Show examples of increasing values with while loops."""
# Counting up to a target
print("Counting up to target:")
counter = 1
target = 5
while counter <= target:
    print(f"  Count: {counter}")
    counter += 1
print(f"  Reached target: {target}")

# Doubling until reaching threshold
print("\nDoubling value until reaching threshold:")
value = 1
threshold = 100
steps = 0
while value < threshold:
    print(f"  Step {steps}: {value}")
    value *= 2
    steps += 1
print(f"  Final value: {value} (exceeded threshold of {threshold})")

# Building a list until condition met
print("\nBuilding list until reaching desired length:")
numbers = []
target_length = 5
current = 1
while len(numbers) < target_length:
    numbers.append(current ** 2)  # Add square of current number
    print(f"  Added {current}² = {current**2}, list: {numbers}")
    current += 1
print(f"  Reached target length: {len(numbers)}")

# Fibonacci sequence until threshold
print("\nFibonacci sequence until value exceeds 50:")
a, b = 0, 1
fibonacci_sequence = [a, b]
while b <= 50:
    next_fib = a + b
    fibonacci_sequence.append(next_fib)
    print(f"  {a} + {b} = {next_fib}")
    a, b = b, next_fib
print(f"  Complete sequence: {fibonacci_sequence}")
demonstrate_value_increase()