The syntax you're looking for:
lambda x: True if x % 2 == 0 else False
But you can't use print or raise in a lambda.
Top answer 1 of 16
913
The syntax you're looking for:
lambda x: True if x % 2 == 0 else False
But you can't use print or raise in a lambda.
2 of 16
49
why don't you just define a function?
def f(x):
if x == 2:
print(x)
else:
raise ValueError
there really is no justification to use lambda in this case.
GeeksforGeeks
geeksforgeeks.org › python › how-to-use-if-else-elif-in-python-lambda-functions
How to use if, else & elif in Python Lambda Functions - GeeksforGeeks
July 23, 2025 - # Use if-else in Lambda Functions # check if two numbers is equal or greater or lesser result = lambda x,y : f"{x} is smaller than {y}" \ if x < y else (f"{x} is greater than {y}" if x > y \ else f"{x} is equal to {y}") # print for numbers ...
can I use an if statement with a lambda function?
It helps to debug if you split your 1 liner into multiple variable steps at each function. I haven't worked with python but it appears the problem may be in your last map. It appears what you want is to filter for len(x['pdd_list']) == 0 in a filter function. .map(lambda x: x['pdd_list']) . filter(lambda x: len(x['pdd_list'])==0) More on reddit.com
4
4
August 12, 2019Using the if, else statement with reduce() and lambda()
Stefan Vaziri is having issues with: I think I got the beginning portion with reduce and lambda right. I think you need to use the if statement here but I'm not sure how to incorpor... More on teamtreehouse.com
3
February 24, 2016pandas - Python lambda function if else condition - Stack Overflow
Question: Trying to understand someone else's code. Can someone please explain what the lambda function is doing here?. Does the lambda function here translates to: If the first 3 digits of OrderNu... More on stackoverflow.com
python - Lambda including if...elif...else - Stack Overflow
Nest if .. elses: lambda x: x*10 if x<2 else (x**2 if x<4 else x+10) More on stackoverflow.com
Videos
02:56
lambda (if else) and (if elif else) condition in Python - YouTube
Python Lambda If Else Statements with Filter() - TUTORIAL
07:08
Python Lambda If Else Statements with Map() - TUTORIAL - YouTube
01:27
Mastering Lambda with If Statements in Python - YouTube
06:50
Learn Python LAMBDA in 6 minutes! 🚮 - YouTube
Spark By {Examples}
sparkbyexamples.com › home › python › python lambda using if else
Python Lambda using if else - Spark By {Examples}
May 31, 2024 - The lambda should have only one expression so here, it should be if-else. The if returns the body when the condition is satisfied, and the else body is returned when the condition is not satisfied.
AskPython
askpython.com › home › lambda with conditional statements in python
Lambda With Conditional Statements in Python - AskPython
October 6, 2023 - We create a lambda object as conditional_lambda. Then, we store a variable x and expression as x/100 from and in joining with that our conditional statement lies. The statement says that if x is less than 20 divide it by 100 else print it as it is.
TutorialsPoint
tutorialspoint.com › article › how-to-use-if-else-amp-elif-in-python-lambda-functions
How to use if, else & elif in Python Lambda Functions
6 days ago - numbers = [1, 2, 3, 4, 5, 6, 7, ... 'Large'] [2, 4, 6, 8, 10] Lambda functions with conditional statements provide a powerful way to create concise, inline decision-making logic in Python....
Python Examples
pythonexamples.org › python-lambda-if-else
Python Lambda - If Else, Nested If Else
You can write an if else or nested if else inside Python lambda function, to conditionally choose values to be returned. In this tutorial, we write Python Lambda Functions with If Else and Nested If Else.
Medium
medium.com › @whyamit101 › using-pandas-lambda-if-else-0d8368b70459
Using pandas lambda if else. The biggest lie in data science? That… | by why amit | Medium
April 12, 2025 - If a certain condition is true, the code within the if block runs; otherwise, the code in the else block runs. Pairing this with a lambda function can make your data transformations quick and efficient.
GeeksforGeeks
geeksforgeeks.org › python › lambda-with-if-but-without-else-in-python
Lambda with if but without else in Python - GeeksforGeeks
July 23, 2025 - Since a lambda function must have a return value for every valid input, we cannot define it with if but without else as we are not specifying what will we return if the if-condition will be false i.e.
Kanoki
kanoki.org › 2022 › 09 › 12 › python-lambda-if-else-elif-with-multiple-conditions-and-filter-list-with-conditions-in-lambda
python lambda if, else & elif with multiple conditions and filter list with conditions in lambda | kanoki
September 12, 2022 - We could also use lambda to loop over a list and evaluate a condition · Let’s define a function with all the conditions that we want to evaluate · def f(grade): if grade > 7: return 'A+' elif grade >= 5 and grade <= 7: return 'A' elif grade <5: return 'B' else: return False ... DataFrames are a powerful tool for working with data in Python, and Pandas provides a number of ways to count duplicate rows in a DataFrame.
GeeksforGeeks
geeksforgeeks.org › python › python-lambda-anonymous-functions-filter-map-reduce
Python Lambda Functions - GeeksforGeeks
The lambda function takes x as input. It uses nested if-else statements to return "Positive," "Negative," or "Zero."
Published 4 days ago
Reddit
reddit.com › r/apachespark › can i use an if statement with a lambda function?
r/apachespark on Reddit: can I use an if statement with a lambda function?
August 12, 2019 -
writing an if statement with a lambda function:
I'm trying to filter a map in spark using an if statement but get a syntax error. I have not been able to find the error. Can you guys tell me what I am doing wrong here?
full_count_with0val = full_rdd.map(lambda x: json.loads(x[1])).flatMap(lambda x: x['exposures']).map(lambda x: x['pdd_list'] if len(x['pdd_list'])==0).take(5)
Top answer 1 of 4
2
It helps to debug if you split your 1 liner into multiple variable steps at each function. I haven't worked with python but it appears the problem may be in your last map. It appears what you want is to filter for len(x['pdd_list']) == 0 in a filter function. .map(lambda x: x['pdd_list']) . filter(lambda x: len(x['pdd_list'])==0)
2 of 4
1
Your lambda with the 'if' needs to return something for the 'else' case. If an element that the lambda was being applied to didn't satisfy the if condition, what would happen to it? If you mean it to not be modified by the lambda, you have to just return it in an else statement. The map function applies the lambda to every element in the RDD. If you only want elements that would match the 'if' condition to remain in the RDD, you should filter the RDD first, then apply the transformation in your if statement after in a map function.
GeeksforGeeks
geeksforgeeks.org › python › using-apply-in-pandas-lambda-functions-with-multiple-if-statements
Using Apply in Pandas Lambda functions with multiple if statements - GeeksforGeeks
June 20, 2025 - Lambda supports only a single if-else, not chained conditions. You can't use elif inside a lambda like in regular Python.
TutorialsPoint
tutorialspoint.com › lambda-with-if-but-without-else-in-python
Lambda with if but without else in Python
July 17, 2023 - The 'otherwise' clause may not always be necessary when using a 'if' statement inside of a lambda function, though. The 'else' clause is required by the syntax of the 'if' statement inside a lambda function in Python.
Top answer 1 of 3
5
You are very much on the right path. I reran the challenge and paused at the same point: the function passed to reduce must process two arguments. How to compare two string with a lambda function. The key is to provide two arguments to the lambda then return the longest:
```python
take two arguments, compare lengths, return longest
lambda string1, string2: string1 if len(string1) > len(string2) else string2, strings
using this lambda in the reduce() along with the 'strings' argument:
longest = reduce(lambda string1, string2: string1 if len(string1) > len(string2) else string2, strings)
```
2 of 3
0
The key is 'find the longest string and store the string' ...NOT find the longest length and store the length in 'longest'.
longest = reduce(lambda x, y: len(x) if len(x) > len(y) else len(y), strings)
This wasn't passing as a result.
Also, watch your spelling of lambda or you'll be like me and keep spelling it lamdba. Can't see the difference. Yeah, neither could I...
Delft Stack
delftstack.com › home › howto › python › python lambda if
if...else in Lambda Function Python | Delft Stack
February 25, 2025 - This tutorial provides a comprehensive guide on using if statements in lambda functions in Python. Learn how to create efficient and readable code with conditional expressions, nested if statements, and filtering techniques. Enhance your Python skills and discover practical examples to implement ...
Python documentation
docs.python.org › 3 › tutorial › controlflow.html
4. More Control Flow Tools — Python 3.14.3 documentation
There can be zero or more elif parts, and the else part is optional. The keyword ‘elif’ is short for ‘else if’, and is useful to avoid excessive indentation. An if … elif …
Stack Overflow
stackoverflow.com › questions › 71260517 › python-lambda-function-if-else-condition › 71260558
pandas - Python lambda function if else condition - Stack Overflow
import sqlalchemy as sq import pandas as pd data_df = pd.read_csv('/dbfs/FileStore/tables/CustomerOrders.txt', sep=',', low_memory=False, quotechar='"', header='infer' , encoding='cp1252') data_df[OrderNumber] = data_df[OrderNumber].apply(lambda x: x if x[:3] != '486' and x[:3] != '561' and x[:1] != '8' else "") .............
Top answer 1 of 4
225
Nest if .. elses:
lambda x: x*10 if x<2 else (x**2 if x<4 else x+10)
2 of 4
50
I do not recommend the use of apply here: it should be avoided if there are better alternatives.
For example, if you are performing the following operation on a Series:
if cond1:
exp1
elif cond2:
exp2
else:
exp3
This is usually a good use case for np.where or np.select.
numpy.where
The if else chain above can be written using
np.where(cond1, exp1, np.where(cond2, exp2, ...))
np.where allows nesting. With one level of nesting, your problem can be solved with,
df['three'] = (
np.where(
df['one'] < 2,
df['one'] * 10,
np.where(df['one'] < 4, df['one'] ** 2, df['one'] + 10))
df
one two three
0 1 6 10
1 2 7 4
2 3 8 9
3 4 9 14
4 5 10 15
numpy.select
Allows for flexible syntax and is easily extensible. It follows the form,
np.select([cond1, cond2, ...], [exp1, exp2, ...])
Or, in this case,
np.select([cond1, cond2], [exp1, exp2], default=exp3)
df['three'] = (
np.select(
condlist=[df['one'] < 2, df['one'] < 4],
choicelist=[df['one'] * 10, df['one'] ** 2],
default=df['one'] + 10))
df
one two three
0 1 6 10
1 2 7 4
2 3 8 9
3 4 9 14
4 5 10 15
and/or (similar to the if/else)
Similar to if-else, requires the lambda:
df['three'] = df["one"].apply(
lambda x: (x < 2 and x * 10) or (x < 4 and x ** 2) or x + 10)
df
one two three
0 1 6 10
1 2 7 4
2 3 8 9
3 4 9 14
4 5 10 15
List Comprehension
Loopy solution that is still faster than apply.
df['three'] = [x*10 if x<2 else (x**2 if x<4 else x+10) for x in df['one']]
# df['three'] = [
# (x < 2 and x * 10) or (x < 4 and x ** 2) or x + 10) for x in df['one']
# ]
df
one two three
0 1 6 10
1 2 7 4
2 3 8 9
3 4 9 14
4 5 10 15
Pythonspot
pythonspot.com › python-lambda
python lambda if - Python Tutorial
For example, if you have the list [1,3,10,4,1] it will return 10 because at some point it will compare 'x=3, y=10: if (3 > 10) return 3 else return 10'. The program keeps repeating the statement 'x if (x > y) else y' until it cannot be applied further.
Mimo
mimo.org › glossary › python › lambda-function
Python Lambda Function: Syntax, Usage, and Examples
Python · Open in Mimo · Open in Mimo · Copy Code · import pandas as pd data = {'Name': ['Alice', 'Bob'], 'Age': [25, 30]} df = pd.DataFrame(data) df['Age Group'] = df['Age'].apply(lambda x: 'Young' if x < 30 else 'Adult') print(df) Use cases in data science include data filtering, transformations, and feature engineering.