Python Conditional Operator

Last Updated on March 15, 2023 by Prepbytes

One of the critical features of Python is its ability to evaluate conditions and execute code based on the outcome of those conditions. This is accomplished through the use of conditional statements, which are also known as if statements. However, Python also provides a shorthand notation for writing if statements known as the Python Conditional Operator.

What is Python Conditional Operator?

The Python conditional operator, also known as the ternary operator, provides a shorthand way of writing an if-else statement. It is a way to evaluate a condition and return one of two values based on the result of that condition. The syntax of the conditional operator is simpler and more concise than an if-else statement, making it a popular choice for many developers.

Syntax of Python Conditional Operator

The syntax of the Python conditional operator is as follows:

value_if_true if condition else value_if_false

In this syntax, the condition is evaluated first. If the condition is true, then value_if_true is returned. Otherwise, value_if_false is returned. The condition can be any expression that returns a boolean value, such as a comparison or a logical operation. The value_if_true and value_if_false can be any expressions that return a value of any data type.

Examples of Python Conditional Operators

Here are some examples of Python conditional operators with explanations and code:

Example – 1 Check if a number is positive or negative
Let’s check if a number is positive or negative using the python conditional operator. Below is the implementation and explanation of the code.

num = 5
result = "Positive" if num > 0 else "Negative"
print(result)  # Output: Positive

Explanation: In this example, we check whether the number num is positive or negative using the conditional operator. If num is greater than zero, the value of the result is set to "Positive". Otherwise, the value of the result is set to "Negative".

Example – 2 Find the maximum of two numbers
Let’s try to find the maximum of two numbers using the python conditional operator. Below is the implementation and explanation of the code.

a = 10
b = 20
max_num = a if a > b else b
print(max_num)  # Output: 20

Explanation: In this example, we find the maximum of two numbers a and b using the conditional operator. If a is greater than b, the value of max_num is set to a. Otherwise, the value of max_num is set to b.

Example – 3 Convert a boolean value to a string
Using the python conditional operator, let’s try to convert a boolean value to a string. Below is the implementation and explanation of the code.

is_valid = True
msg = "Valid" if is_valid else "Invalid"
print(msg)  # Output: Valid

Explanation: In this example, we convert a boolean value is_valid to a string using the conditional operator. If is_valid is True, the value of msg is set to "Valid". Otherwise, the value of msg is set to "Invalid".

Example – 4 Check if a string is empty
Let’s check if a string is empty or not using the python conditional operator. Below is the implementation and explanation of the code.

string = "hello"
result = "Not Empty" if string else "Empty"
print(result)  # Output: Not Empty

Explanation: In this example, we check whether a string is empty or not using the conditional operator. If the string is not empty, the value of the result is set to "Not Empty". Otherwise, the value of the result is set to "Empty".

Example – 5 Convert a number to its absolute value
Let’s try to convert a number to its absolute value by using the python conditional operator. Below is the implementation and explanation of the code.

num = -10
abs_num = num if num >= 0 else -num
print(abs_num)  # Output: 10

Explanation: In this example, we convert a number num to its absolute value using the conditional operator. If num is greater than or equal to zero, the value of abs_num is set to num. Otherwise, the value of abs_num is set to -num.

Example – 6 Check if a list is empty
Using the python conditional operator let’s check if a list is empty or not. Below is the implementation and explanation of the code.

my_list = [1, 2, 3]
result = "Not Empty" if my_list else "Empty"
print(result)  # Output: Not Empty

Explanation: In this example, we check whether a list my_list is empty or not using the conditional operator. If my_list is not empty, the value of the result is set to "Not Empty". Otherwise, the value of the result is set to "Empty".

Nested Python Conditional Operator

A nested Python conditional operator is an expression that contains one or more conditional operators within another conditional operator. The nested conditional operator allows for more complex conditions to be evaluated in a concise and efficient way.

The syntax for a nested conditional operator is similar to that of a regular conditional operator:

value_if_true if condition1 else value_if_false if condition2 else value_if_false2

In this example, if condition1 is true, then value_if_true is returned. If condition1 is false, then condition2 is evaluated. If condition2 is true, then value_if_false is returned. If condition2 is false, then value_if_false2 is returned.

Here is an example of a nested conditional operator that checks the sign of a number:

num = 5
result = "Positive" if num > 0 else ("Zero" if num == 0 else "Negative")
print(result)   #output: Positive

Explanation: In this example, the first condition num > 0 checks whether num is positive. If it is, then "Positive" is returned. If num is not positive, then the second condition num == 0 checks whether num is equal to zero. If it is, then "Zero" is returned. If num is not equal to zero, then "Negative" is returned.

Using a nested conditional operator can simplify code and make it more efficient by avoiding unnecessary computations. However, it is important to ensure that the conditions are evaluated in the correct order and that the resulting code is still readable and maintainable.

Examples of Nested Python Conditional Operator

Here are some more examples of Nested Python conditional operators with explanation and code:

Example 1: Check if a number is divisible by both 2 and 3
Below is the code implementation and explanation.

num = 6
result = "Divisible by both" if num % 2 == 0 and num % 3 == 0 else "Not divisible by both"
print(result)   # output: Divisible by both

Explanation: In this example, the condition num % 2 == 0 and num % 3 == 0 checks if num is divisible by both 2 and 3. If it is, then "Divisible by both" is returned. Otherwise, "Not divisible by both" is returned.

Example 2: Determine the grade based on a student’s score
Below is the implementation and explanation of the code.

score = 75

grade = "A" if score >= 90 else ("B" if score >= 80 else ("C" if score >= 70 else ("D" if score >= 60 else "F")))
print(grade)  #output: C

Explanation: In this example, the nested conditional operator checks the score against multiple conditions to determine the grade. If the score is greater than or equal to 90, an "A" grade is returned. If the score is between 80 and 89, a "B" grade is returned, and so on, until a failing grade of "F" is returned if none of the other conditions are met.

Example 3: Calculate the maximum of three numbers
Below is the implementation and explanation of the code.

a, b, c = 4, 9, 2
max_num = a if a > b else b if b > c else c
print(max_num)  #Output: 9 

Explanation: In this example, the nested conditional operator is used to determine the maximum of three numbers. Condition a > b is evaluated first. If it is true, then a is returned as the maximum. If it is false, then b > c is evaluated. If it is true, then b is returned as the maximum. If it is false, then c is returned as the maximum.

Conclusion
Python conditional operator provides a concise way to write if-else statements. Instead of writing multiple lines of code to perform a simple check, a single line of code can be used to return one value if a condition is true and another value if it is false. The syntax for Python conditional operator is straightforward and easy to understand, and they can be used in a variety of situations, from simple checks to more complex nested conditions. Understanding how to use Python conditional operator can make code more efficient and readable, which is crucial for creating maintainable software. By combining the flexibility of Python conditional operator with an understanding of how to use them effectively, developers can write more concise and robust code that meets the needs of their projects.

FAQs

Here are some frequently asked questions (FAQs) about the Python conditional operator:

Q1 – What is the difference between an if-else statement and a conditional operator?
Ans – An if-else statement is used to execute a block of code if a certain condition is met, whereas a conditional operator is used to return one of two values based on the outcome of a condition. The conditional operator is a shorthand notation for writing if-else statements and can be used to simplify code.

Q2 – Can a conditional operator be used to replace if-else statements in all cases?
Ans – No, a conditional operator is not always the best choice for replacing if-else statements, especially for more complex conditions that require multiple levels of nesting. In such cases, using an if-else statement may make the code more readable.

Q3 – Can a conditional operator be used in place of an if-else statement in list comprehensions?
Ans – Yes, a conditional operator can be used in place of an if-else statement in list comprehensions. For example, my_list = [x if x > 0 else 0 for x in nums].
This code returns a new list my_list that contains the elements of the original list nums if they are greater than zero, or zero if they are not.

Q4 – Can a conditional operator be used in place of an if-else statement in lambda functions?
Ans – Yes, a conditional operator can be used in place of an if-else statement in lambda functions. For example, f = lambda x: x if x > 0 else 0. This code defines a lambda function f that returns x if it is greater than zero or zero if it is not.

Q5 – Can a conditional operator be nested within another conditional operator?
Ans – Yes, a conditional operator can be nested within another conditional operator. For example, result = "Positive" if num > 0 else ("Zero" if num == 0 else "Negative"). This code checks whether the number num is positive, zero, or negative, and returns the corresponding string value.

Q6 – Is the conditional operator evaluated from left to right?
Ans – Yes, the conditional operator is evaluated from left to right. The expressions value_if_true and value_if_false are only evaluated if their corresponding condition is met. This means that the conditional operator can be used to avoid unnecessary computations.