1 if A else 2 if B else 3 translates to this:
def myexpr(A, B):
if A:
return 1
else:
if B:
return 2
else:
return 3
Your ternary expression can be interpreted with parentheses as follows:
(
(1 if A) else (
(2 if B) else 3
)
)
Top answer 1 of 5
28
1 if A else 2 if B else 3 translates to this:
def myexpr(A, B):
if A:
return 1
else:
if B:
return 2
else:
return 3
Your ternary expression can be interpreted with parentheses as follows:
(
(1 if A) else (
(2 if B) else 3
)
)
2 of 5
7
Could someone please explain why this is executed in this order, and possibly suggest some material that gives an intuition about why this is used/preferred?
I'm trying to answer the "intuition" part of your question by solving a simple but more general problem.
'''
+-----------------------------------------------------------------------------------+
| Problem: |
+-----------------------------------------------------------------------------------+
| Convert a |
| nested if-else block into |
| a single line of code by using Pythons ternary expression. |
| In simple terms convert: |
| |
| 1.f_nested_if_else(*args) ( which uses |
| ```````````````````` nested if-else's) |
| | |
| +--->to its equivalent---+ |
| | |
| V |
| 2.f_nested_ternary(*args) ( which uses |
| ``````````````````` nested ternary expression) |
+-----------------------------------------------------------------------------------+
'''
'''
Note:
C:Conditions (C, C1, C2)
E:Expressions (E11, E12, E21, E22)
Let all Conditions, Expressions be some mathematical function of args passed to the function
'''
#-----------------------------------------------------------------------------------+
#| 1. | Using nested if-else |
#-----------------------------------------------------------------------------------+
def f_nested_if_else(*args):
if(C):
if(C1):
return E11
else:
return E12
else:
if(C2):
return E21
else:
return E22
#-----------------------------------------------------------------------------------+
#| 2. | Using nested ternary expression |
#-----------------------------------------------------------------------------------+
def f_nested_ternary(*args):
return ( (E11) if(C1)else (E12) ) if(C)else ( (E21) if(C2)else (E22) )
#-----------------------------------------------------------------------------------+
#-----------------------------------------------------------------------------------|
#-----------------------------------------------------------------------------------|
#-----------------------------------------------------------------------------------|
#-----------------------------------------------------------------------------------+
Here is a visualization of why f_nested_if_else() and f_nested_ternary() are equivalent.
# +-----------------------------------------------------------------------------+
# | Visualization: |
# +-----------------------------------------------------------------------------+
# | Visualize the ternary expression like a binary tree : |
# | -Starting from the root and moving down to the leaves. |
# | -All the internal nodes being conditions. |
# | -All the leaves being expressions. |
# +-----------------------------------------------------------------------------+
_________________
|f_nested_ternary|
``````````````````
( (E11) if(C1)else (E12) ) if(C)else ( (E21) if(C2)else (E22) )
| | | | | | |
| | | | | | |
V V V V V V V
Level-1| +----------------(C)-----------------+
-------- True/ __________________ \False
V |f_nested_if_else| V
Level-2| +----(C1)----+ `````````````````` +----(C2)----+
-------- True/ \False True/ \False
V V V V
Level-3| ( (E11) (E12) ) ( (E21) (E22) )
------------------------------------------------------------------------------------+
Hope this visualization gave you an intuition of how nested ternary expressions are evaluated :P
DataCamp
datacamp.com › tutorial › pythons-ternary-operators-guide
Python's Ternary Operators Guide: Boosting Code Efficiency | DataCamp
May 17, 2024 - The nested ternary operator in Python allows you to combine multiple conditional expressions within a single ternary operator.
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GeeksforGeeks
geeksforgeeks.org › python › ternary-operator-in-python
Ternary Operator in Python - GeeksforGeeks
We can nest ternary operators to evaluate multiple conditions in a single line. ... First, it checks if num > 0. If True, it returns "Positive". If False, it checks if num < 0. If True, it returns "Negative".
Published December 20, 2025
Reddit
reddit.com › r/python › one line if else and nested if statements in python ( ternary operator)
r/Python on Reddit: One line if else and nested if statements in python ( ternary operator)
July 8, 2020 - One ternary is often confusing enough, nesting them makes the code unnecessarily unreadable. when your colleagues or (more often) you read this code in 6 months you will thank yourself for not doing this. there is no advantage in doing this instead of using elif statements ... And I'd even say be also careful with simple ternary operators too.
Wiingy
wiingy.com › home › learn › python › ternary operators in python
Ternary Operators in Python
January 30, 2025 - The nested ternary operator checks if the numberis zero by evaluating num == 0. If the condition is true, the nested ternary operator returns the string “zero”. If both the first and nested conditions are false, the ternary operator returns ...
Python Examples
pythonexamples.org › python-ternary-operator
Python Ternary Operator
This example demonstrates that you can run any Python function inside a Ternary Operator. You can nest a ternary operator in another statement with ternary operator.
Finxter
blog.finxter.com › python-nested-multiple-ternary-operators
Python Nested Multiple Ternary Operators – Be on the Right Side of Change
Short Answer: The nested ternary operator '1' if x else '2' if y else '3' evaluates the condition from left to right, i.e., '1' if x else ('2' if y else '3').
DataFlair
data-flair.training › blogs › python-ternary-operator
Python Ternary Operator - 5 Ways To Implement Ternary Operators - DataFlair
July 14, 2025 - We can also make use of Python Lambda Functions to act as a ternary operator. ... >>> a=random() >>> "Less than zero" if a<0 else "Between 0 and 1" if a>=0 and a<=1 else "Greater than one" ...
Codecademy
codecademy.com › article › python-ternary-operator
Guide to Using Ternary Operator in Python | Codecademy
When using the ternary operator ... conditions that can be easily understood at a glance. Avoid Nesting: Limit the nesting of the ternary operator ......
Top answer 1 of 3
30
Your first example (the horrid one-liner) is nested too. Horizontally nested. Your second example is vertically nested. They're both nested.
So which is better? The second one! Why? Because "sparse is better than dense" breaks the tie.
It's easy when you're Tim Peters - LOL ;-)
2 of 3
3
"Flat is better than nested" is about module organization and perhaps data structures, not your source code. The standard library, for example, mostly exists as top-level modules with very little nesting.
Don't nest the ternary operator, or even use it at all if you can avoid it. Complex is better than complicated. :)
Enterprise DNA
blog.enterprisedna.co › ternary-operator-in-python-what-how-why
Ternary Operator in Python – What? How? Why? – Master Data Skills + AI
When using the ternary operator in Python, there are some best practices and tips to help you write clean, efficient, and readable code. Firstly, ensure that your conditional expression is short and concise. Long and complex conditions might make it difficult to understand the logic behind the ternary operator. If you find yourself facing a complex condition, it might be better to use a regular if-else statement instead. #demonstrate nested ternary operator # Good example result = "positive" if number >= 0 else "negative" # Bad example result = (a + b if (x > 10 and y > 20) else c + d) if (z > 30 and p > 40) else ...
Dataquest
dataquest.io › blog › python-ternary-operator
Python Ternary: How to Use It and Why It's Useful (with Examples)
March 6, 2023 - The Python ternary operator (or conditional operator), tests if a condition is true or false and, depending on the outcome, returns the corresponding value — all in just one line of code.
Igmguru
igmguru.com › blog › ternary-operator-in-python
Ternary Operator in Python: Complete Tutorial for Beginners
4 days ago - There is no significant performance difference between the ternary operator and a traditional if-else statement. These both are evaluated efficiently by Python. The main advantage of the ternary operator is cleaner and shorter syntax for simple conditions. Yes, multiple conditions can be used by nesting ternary operators.
Python Geeks
pythongeeks.org › python geeks › learn python › python ternary operator with example
Python Ternary Operator with Example - Python Geeks
June 14, 2022 - # Take Input of Number no = int(input()) # Nested Ternary Operators Implementation PythonGeeks_result = "Negative Number" if no<0 else "Number is Zero" if no==0 else "Positive Number" # Displaying the result print("Result for ",no," : ",PythonGeeks_result)
Mimo
mimo.org › glossary › python › ternary-operator
Python Ternary Operator: Syntax, Usage, and Examples
Python doesn’t allow assignment expressions like JavaScript does. ... Each case allows you to replace bulky conditional logic with one clear, compact line. The Python ternary operator gives you a flexible and readable way to handle conditional assignments and expressions.
DEV Community
dev.to › askyt › python-ternary-operator-a-comprehensive-guide-274i
Python Ternary Operator: A Comprehensive Guide - DEV Community
December 14, 2024 - The ternary operator simplifies ... than zero" if x > 0 else "Equal to zero" print(result) ... Note: While nesting is possible, it can harm readability....
Scaler
scaler.com › home › topics › python › ternary operator in python
Ternary Operator in Python - Scaler Topics
April 21, 2023 - We can nest ternary operators by chaining them. We should avoid nesting as it may hurt readability. Also, check out this article to learn about Operators in Python.
iO Flood
ioflood.com › blog › python-ternary-operator
Python Ternary Operator | Usage Guide with Examples
February 4, 2024 - As a best practice, avoid nesting ternary operations more than once. If your code requires more complex conditional logic, consider using traditional if-else statements for clarity. Remember, the goal of using the ternary operator should be to make your code more readable and efficient, not less. While the ternary operator is a powerful tool, Python ...
AlgoMaster
algomaster.io › learn › python › ternary-operator
Ternary Operator | Python | AlgoMaster.io | AlgoMaster.io
Use for Simple Conditions: Reserve the ternary operator for straightforward cases where it enhances readability. Avoid Excessive Nesting: Limit nesting to maintain clarity.
GUVI
guvi.in › hub › python › ternary-operator-in-python
The Ternary Operator in Python
In the above code snippet, the nested ternary operator first checks if the number is even. ... Otherwise, another ternary operator is used to determine if the number is positive or negative. Using the ternary operator in Python offers several benefits, including: