The Ternary if Statement in Python

In one of the previous articles we were talking about conditional statements. Today we’ll be talking about the ternary if statement.

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We can simplify short conditional statements and the blocks that follow by using the so-called ternary if statement. Here’s a simple regular piece of conditional code:

 >>> a, b = 7, 3
 >>> if(a > b):
 ...     winner = a
 ... else:
 ...     winner = b
 ...  

We can now rewrite the code using the ternary if statement:

 winner = a if (a > b) else b 

The general syntax is:

 x = a if(condition) else b 

So, a is assigned to x provided the condition is met. Otherwise, b is assigned to x.

Ternary if Statement in Expressions

The ternary if statement can be also used in expressions, like for example:

 >>> a, b = 5, 8
 >>> result = 4 * (a if (a != b) else b ** 2) / 2
 >>> result
 10.0 

The condition to check here is whether a is not equal to b. As a equals 5 and b equals 8, they’re definitely not equal, so the condition is met. This entails using the value of a, which is 5, in the calculations:

 4 * 5 / 2 = 10.0

Now, let’s make the two variables equal:

 >>> a = b = 5
 >>> result = 4 * (a if (a != b) else b ** 2) / 2
 >>> result
 50.0 

Now the condition is not met, so b ** 2 is chosen for the calculations:

 4 * 5 ** 2 / 2 = 4 * 25 / 2 = 50.0