Python Cheat Sheet: The Ternary Operator 🚀

Shorten your if/else statements for compact, one-line value selection. It's also known as a conditional expression.

#### 📜 The Standard if/else Block

This is the classic, multi-line way to assign a value based on a condition.

# Check if a user is an adult
age = 20
status = ""

if age >= 18:
    status = "Adult"
else:
    status = "Minor"

print(status)
# Output: Adult

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#### ✅ The Ternary Operator (One-Line if/else)

The same logic can be written in a single, clean line.

Syntax:
value_if_true if condition else value_if_false

Let's rewrite the example above:

age = 20

# Assign 'Adult' if age >= 18, otherwise assign 'Minor'
status = "Adult" if age >= 18 else "Minor"

print(status)
# Output: Adult

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💡 More Examples

The ternary operator is an expression, meaning it returns a value and can be used almost anywhere.

1. Inside a Function return

def get_fee(is_member):
    # Return 5 if they are a member, otherwise 15
    return 5.00 if is_member else 15.00

print(f"Your fee is: ${get_fee(True)}")
# Output: Your fee is: $5.0
print(f"Your fee is: ${get_fee(False)}")
# Output: Your fee is: $15.0

2. Inside an f-string or print()

is_logged_in = False

print(f"User status: {'Online' if is_logged_in else 'Offline'}")
# Output: User status: Offline

3. With List Comprehensions (Advanced)

This is where it becomes incredibly powerful for creating new lists.

numbers = [1, 10, 5, 22, 3, -4]

# Create a new list labeling each number as "even" or "odd"
labels = ["even" if n % 2 == 0 else "odd" for n in numbers]
print(labels)
# Output: ['odd', 'even', 'odd', 'even', 'odd', 'even']

# Create a new list of only positive numbers, or 0 for negatives
sanitized = [n if n > 0 else 0 for n in numbers]
print(sanitized)
# Output: [1, 10, 5, 22, 3, 0]

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🧠 When to Use It (and When Not To!)

• DO use it for simple, clear, and readable assignments. If it reads like a natural sentence, it's a good fit.

• DON'T use it for complex logic or nest them. It quickly becomes unreadable.

❌ BAD EXAMPLE (Avoid This!):

# This is very hard to read!
x = 10
message = "High" if x > 50 else ("Medium" if x > 5 else "Low")

✅ BETTER (Use a standard if/elif/else for clarity):

x = 10
if x > 50:
    message = "High"
elif x > 5:
    message = "Medium"
else:
    message = "Low"

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By: @DataScience4 ✨