Python Ternary Operator – 5 Ways To Implement Ternary Operators

Today, we will see Python Ternary Operator. Moreover, we will discuss the example and syntax of Ternary Operator in Python.

Also, we will learn before and nested Python Ternary Operators. At last, we will discuss ways for implementing Ternary operators in Python.

So, let’s start Python Ternary Operator.

Python Ternary Operator – Implementation With Example

What is Python Ternary Operator?

Ternary operators in Python are terse conditional expressions. These are operators that test a condition and based on that, evaluate a value.

This was made available since PEP 308 was approved and is available ever since version 2.4. This operator, if used properly, can reduce code size and enhance readability.

1. Python if-else code

Let’s write code to compare two integers.

>>> a,b=2,3
>>> if a>b:
        print("a")
else:
        print("b")

Output

2. Equivalent code with Ternary operator

So let’s try doing the same with ternary operators:

>>> a,b=2,3
>>> print("a" if a>b else "b")

Output

Voila! Done in one line. Python first evaluates the condition. If true, it evaluates the first expression; otherwise, it evaluates the second.

There is a lazy evaluation. It also evaluates the conditions left to right.

The syntax for Python Ternary Operator

Now, let’s learn a little the syntax for Python Ternary Operator.

[on_true] if [expression] else [on_false]

In C++, it looks like this:

max=(a>b)?a:b

But this isn’t quite Pythonic, so Guido, Python’s BDFL (a status from which he has resigned permanently), rejected it.

Another reason for the veto is that we already have many uses for the colon(:).

One more example of Python ternary Operators:

>>> from random import random
>>> a,b=random(),random()
>>> res="a" if a>b else "b"
>>> res

Output

>>> a,b

Output

Ways to Implement Ternary Operator

Below, we are discussing different ways of implementing Python Ternary Operator:

Ways to Implement Ternary Operator

1. Using Python Tuples

We can use tuples to specify what to do if the condition is True/False.

>>> a,b=random(),random()
>>> (b,a)[a>b]

Output

This is equivalent to:

>>> (b,a)[True]

But we’re confused which this is- a or b. Let’s try tweaking this.

>>> (f"b:{b}",f"a:{a}")[a>b]

Output

That’s more like it. Looking at the code, you’ll reckon the first argument in the tuple corresponds to a Boolean value of False; the second- True. This is because of False=0 and True=1. The condition resides within the [ ].

Note that this method evaluates both elements of the tuple, and hence is less efficient. This happens because it must first build the tuple before it can look for an index.

>>> condition=True
>>> 2 if condition else 1/0    #Follows the normal if-else logic tree

Output

>>> (1/0,2)[condition]

Output

2. Using Python Dictionaries

Likewise, we can make this happen using dictionaries with the same logic.

>>> a,b=random(),random()
>>> {False:f"b:{b}",True:f"a:{a}"}[a>b]

Output

Since we specify what to do when here, we can interchange the positions of key-value pairs.

>>> {True:f"a:{a}",False:f"b:{b}"}[a>b]

Output

3. Using Lambdas

We can also make use of Python Lambda Functions to act as a ternary operator.

>>> (lambda :f"b:{b}",lambda :f"a:{a}")[a>b]()

Output

Nested Python Ternary Operator

Let’s try chaining these operators, shall we?

>>> a=random()
>>> "Less than zero" if a<0 else "Between 0 and 1" if a>=0 and a<=1 else "Greater than one"

Output

>>> a

Output

Here, we check for the value of a. If it falls shorter than 0, we print “Less than zero”; if between 0 and 1, we print “Between 0 and 1”. Else, we print “Greater than one”. Notice how we nested them.

Before Ternary Operators in Python

Before this was a thing with Python, this is what we did (we used a common idiom):

>>> a,b=2,3
>>> a<b and a or b

Output

So how does this work? Let’s see.

• a is 2 and b is 3
• It checks if a<b
• If true, it gives us True and a or b
• This gives us a or b
• It checks a
• If false, it gives us False or b
• This gives us b

This method, however, doesn’t work for a=0. This is because that would be True and 0 or b, which is True and False or b, which is False or b, which is b. Oops!

Now why don’t you try formulating an expression for a>b and try explaining it to yourself?

It could also be beneficial to use the and/or logic when one of our expressions is the same as the condition:

>>> def sayhello(): print('Hello')
>>> sayhello() if sayhello() else 'Bye'

Output

>>> sayhello() or 'Bye'

Output

So, this was all in Python Ternary Operator. Hope you like our explanation.

Python Interview Questions on Ternary Operator

1. Does Python have a Ternary operator?
2. How do you use a Python Ternary operator?
3. Explain Python ternary operator with example?
4. What is Python ternary operator symbol?
5. Are Python ternary operators readable?

Conclusion

Phew! That’s all. Through this Python Ternary Operator blog, we tried our best to bring to you all there is to know about the ternary operator in Python. Moreover, we discussed the implementation of Ternary Operators in Python.

Also, we saw Python Ternary Operators example and syntax. We curated our content from the best sources. Like this tutorial?

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