Is there a ternary conditional operator in Python?

Yes, Python has a ternary conditional operator (often called a “ternary expression”) that allows you to write simple conditional logic in a single line. Its syntax is:

value_if_true if condition else value_if_false

How It Works

If condition evaluates to True, the expression returns value_if_true.
If condition evaluates to False, it returns value_if_false.

Example 1: Basic Usage

x = 10
result = "Even" if x % 2 == 0 else "Odd"
print(result)  # Output: "Even"

Example 2: Assigning Numeric Values

age = 25
category = "Adult" if age >= 18 else "Minor"
print(category)  # Output: "Adult"

Example 3: Nested Ternary (Use Sparingly!)

score = 85
grade = (
    "A" if score >= 90 else
    "B" if score >= 80 else
    "C" if score >= 70 else
    "F"
)
print(grade)  # Output: "B"

Key Notes

Order Matters:
The structure is [true_value] if [condition] else [false_value] (unlike C/JavaScript’s condition ? true_value : false_value).
Readability:
Use it for simple conditions only. For complex logic, stick to if-elif-else blocks.
Both Branches Are Required:
The else clause is mandatory. This will throw an error:

   # SyntaxError: invalid syntax
   value = "Yes" if condition

Works with All Data Types:
You can return strings, numbers, objects, or even functions:

   # Return a function
   action = save_data if user_is_valid else log_error

Common Use Cases

Variable Assignment:

  discount = 0.2 if is_member else 0.05

Function Arguments:

  print(f"Status: {'Active' if is_active else 'Inactive'}")

List Comprehensions:

  numbers = [1, 2, 3, 4]
  squared = [x**2 if x % 2 == 0 else x for x in numbers]
  # Output: [1, 4, 3, 16]

Avoid Misusing It

While ternary expressions are concise, overusing them can hurt readability. Compare:

Good (simple condition):

message = "Success" if status_code == 200 else "Error"

Bad (nested complexity):

# Hard to read! Use `if-elif-else` instead.
result = "A" if x > 90 else "B" if x > 80 else "C" if x > 70 else "F"

Pure JavaScript Comparison

For developers familiar with JavaScript:

// JavaScript
const result = condition ? true_value : false_value;

# Python
result = true_value if condition else false_value

In summary, Python’s ternary operator is a compact way to handle simple conditionals.