Python Lambda Functions Practice Questions with Solutions

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Lambda functions are small anonymous functions in Python. They are useful when you need a simple function for a short period of time. In this practice set, you’ll learn how to create lambda functions, pass arguments, use them with built-in functions, and solve beginner-friendly Python programs. Python lambda functions practice questions with solutions help to understand this concepts.

1. Python Program to Create a Simple Lambda Function

Problem Statement

Write a Python lambda function to add 10 to a given number.

Python Solution

add_ten = lambda number: number + 10

print(add_ten(15))

Sample Output

25

Explanation

A lambda function is created using the lambda keyword and returns the result automatically.

Concepts Covered

  • lambda keyword
  • Anonymous Function

2. Python Program to Add Two Numbers Using Lambda

Problem Statement

Write a Python lambda function to add two numbers.

Python Solution

add = lambda a, b: a + b

print(add(20, 15))

Sample Output

35

Explanation

Lambda functions can accept multiple arguments just like normal functions.

Concepts Covered

  • Lambda Arguments

3. Python Program to Find the Square of a Number Using Lambda

Problem Statement

Write a Python lambda function to calculate the square of a number.

Python Solution

square = lambda number: number ** 2

print(square(9))

Sample Output

81

Explanation

The lambda function returns the square of the given number.

Concepts Covered

  • Exponent Operator
  • Lambda Function

4. Python Program to Find the Maximum of Two Numbers Using Lambda

Problem Statement

Write a Python lambda function to return the larger of two numbers.

Python Solution

maximum = lambda a, b: a if a > b else b

print(maximum(25, 40))

Sample Output

40

Explanation

The conditional expression selects the greater value.

Concepts Covered

  • Conditional Expression
  • Lambda Function

5. Python Program to Sort a List of Numbers Using Lambda

Problem Statement

Write a Python program to sort a list in ascending order using a lambda function.

Python Solution

numbers = [45, 12, 78, 23, 9]

numbers.sort(key=lambda number: number)

print(numbers)

Sample Output

[9, 12, 23, 45, 78]

Explanation

The key parameter accepts a lambda function that defines the sorting rule.

Concepts Covered

  • sort()
  • key
  • lambda

6. Python Program to Sort a List of Tuples Using Lambda

Problem Statement

Write a Python program to sort students by age.

Python Solution

students = [
    ("Amit", 22),
    ("Rahul", 19),
    ("Neha", 21)
]

students.sort(key=lambda student: student[1])

print(students)

Sample Output

[('Rahul', 19), ('Neha', 21), ('Amit', 22)]

Explanation

The lambda function uses the second value (age) as the sorting key.

Concepts Covered

  • List of Tuples
  • Lambda Sorting

7. Python Program to Use Lambda with map()

Problem Statement

Write a Python program to double every number in a list using map() and a lambda function.

Python Solution

numbers = [2, 4, 6, 8]

result = list(map(lambda number: number * 2, numbers))

print(result)

Sample Output

[4, 8, 12, 16]

Explanation

The map() function applies the lambda function to every element.

Concepts Covered

  • map()
  • Lambda Function

8. Python Program to Use Lambda with filter()

Problem Statement

Write a Python program to filter even numbers from a list using filter() and a lambda function.

Python Solution

numbers = [10, 15, 20, 25, 30, 35]

result = list(filter(lambda number: number % 2 == 0, numbers))

print(result)

Sample Output

[10, 20, 30]

Explanation

The filter() function keeps only the elements that satisfy the condition.

Concepts Covered

  • filter()
  • Lambda Function

9. Python Program to Use Lambda with sorted()

Problem Statement

Write a Python program to sort words based on their length.

Python Solution

words = ["Python", "AI", "Programming", "Code"]

result = sorted(words, key=lambda word: len(word))

print(result)

Sample Output

['AI', 'Code', 'Python', 'Programming']

Explanation

The sorted() function uses the lambda function to compare word lengths.

Concepts Covered

  • sorted()
  • len()
  • Lambda Function

10. Python Program to Find the Cube of a Number Using Lambda

Problem Statement

Write a Python lambda function to calculate the cube of a number.

Python Solution

cube = lambda number: number ** 3

print(cube(5))

Sample Output

125

Explanation

The lambda function returns the cube of the given number using the exponent operator.

Concepts Covered

  • Lambda Function
  • Exponent Operator

11. Python Program to Sort a List of Dictionaries by Salary Using Lambda

Problem Statement

Write a Python program to sort a list of employee dictionaries in descending order based on salary using a lambda function.

Python Solution

employees = [
    {"Name": "Rahul", "Salary": 45000},
    {"Name": "Priya", "Salary": 62000},
    {"Name": "Aman", "Salary": 51000},
    {"Name": "Neha", "Salary": 70000}
]

employees.sort(
    key=lambda employee: employee["Salary"],
    reverse=True
)

print("Employees Sorted by Salary:\n")

for employee in employees:
    print(employee)

Sample Output

Employees Sorted by Salary:

{'Name': 'Neha', 'Salary': 70000}
{'Name': 'Priya', 'Salary': 62000}
{'Name': 'Aman', 'Salary': 51000}
{'Name': 'Rahul', 'Salary': 45000}

Explanation

The lambda function extracts the "Salary" value from each dictionary, allowing the sort() method to arrange employees in descending order.

Concepts Covered

  • Lambda Functions
  • sort()
  • Dictionary Sorting
  • Lists

12. Python Program to Filter Prime Numbers Using Lambda and filter()

Problem Statement

Write a Python program to filter prime numbers from a list using a lambda function with the filter() function.

Python Solution

numbers = [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17]

is_prime = lambda n: (
    n > 1 and all(n % i != 0 for i in range(2, int(n ** 0.5) + 1))
)

prime_numbers = list(filter(is_prime, numbers))

print("Prime Numbers:")
print(prime_numbers)

Sample Output

Prime Numbers:
[2, 3, 5, 7, 11, 13, 17]

Explanation

The lambda function checks whether a number is prime, and filter() keeps only the numbers that satisfy the condition.

Concepts Covered

  • Lambda Functions
  • filter()
  • Prime Numbers
  • all()

13. Python Program to Calculate the Product of List Elements Using Lambda and reduce()

Problem Statement

Write a Python program to calculate the product of all numbers in a list using a lambda function and the reduce() function.

Python Solution

from functools import reduce

numbers = [2, 3, 4, 5]

product = reduce(
    lambda x, y: x * y,
    numbers
)

print("Product =", product)

Sample Output

Product = 120

Explanation

The reduce() function repeatedly applies the lambda function to combine all elements into a single product.

Concepts Covered

  • Lambda Functions
  • reduce()
  • functools Module
  • Multiplication

14. Python Program to Sort Strings by Their Length Using Lambda

Problem Statement

Write a Python program to sort a list of strings based on their length using a lambda function.

Python Solution

languages = [
    "Python",
    "C",
    "Java",
    "JavaScript",
    "SQL",
    "Go"
]

sorted_languages = sorted(
    languages,
    key=lambda language: len(language)
)

print("Sorted List:")
print(sorted_languages)

Sample Output

Sorted List:
['C', 'Go', 'SQL', 'Java', 'Python', 'JavaScript']

Explanation

The lambda function returns the length of each string, allowing the sorted() function to arrange the list by string length.

Concepts Covered

  • Lambda Functions
  • sorted()
  • len()
  • String Sorting

15. Python Program to Find Students Scoring More Than 80 Marks Using Lambda

Problem Statement

Write a Python program to filter students who scored more than 80 marks using a lambda function.

Python Solution

students = {
    "Rahul": 76,
    "Priya": 92,
    "Aman": 81,
    "Neha": 88,
    "Rohit": 65
}

top_students = dict(
    filter(
        lambda student: student[1] > 80,
        students.items()
    )
)

print("Students Scoring More Than 80 Marks:")
print(top_students)

Sample Output

Students Scoring More Than 80 Marks:
{'Priya': 92, 'Aman': 81, 'Neha': 88}

Explanation

The items() method converts the dictionary into key-value pairs. The lambda function filters only those students whose marks are greater than 80, and the filtered result is converted back into a dictionary.

Concepts Covered

  • Lambda Functions
  • filter()
  • Dictionary
  • items()
  • Conditional Filtering

16. Python Program to Find the Student with the Highest Average Marks Using Lambda

Problem Statement

Write a Python program to find the student with the highest average marks from a dictionary containing subject-wise marks using a lambda function.

Python Solution

students = {
    "Rahul": [85, 90, 88],
    "Priya": [95, 96, 94],
    "Aman": [78, 82, 80],
    "Neha": [91, 89, 93]
}

top_student = max(
    students.items(),
    key=lambda student: sum(student[1]) / len(student[1])
)

average = sum(top_student[1]) / len(top_student[1])

print("Top Student:", top_student[0])
print("Average Marks:", round(average, 2))

Sample Output

Top Student: Priya
Average Marks: 95.0

Explanation

The lambda function calculates the average marks for each student. The max() function returns the student with the highest average score.

Concepts Covered

  • Lambda Functions
  • max()
  • Dictionary
  • Average Calculation

17. Python Program to Remove Duplicate Strings Using Lambda

Problem Statement

Write a Python program to remove duplicate strings from a list while preserving the original order using a lambda function.

Python Solution

words = [
    "Python",
    "Java",
    "Python",
    "SQL",
    "Java",
    "C++",
    "Python"
]

remove_duplicates = lambda data: list(dict.fromkeys(data))

result = remove_duplicates(words)

print("Unique Words:")
print(result)

Sample Output

Unique Words:
['Python', 'Java', 'SQL', 'C++']

Explanation

The lambda function uses dict.fromkeys() to eliminate duplicate values while maintaining the insertion order.

Concepts Covered

  • Lambda Functions
  • dict.fromkeys()
  • Lists
  • Duplicate Removal

18. Python Program to Sort Tuples by Multiple Fields Using Lambda

Problem Statement

Write a Python program to sort employee records first by department and then by salary using a lambda function.

Python Solution

employees = [
    ("Rahul", "HR", 45000),
    ("Priya", "IT", 65000),
    ("Aman", "IT", 50000),
    ("Neha", "HR", 70000),
    ("Rohit", "Sales", 42000)
]

sorted_data = sorted(
    employees,
    key=lambda employee: (employee[1], employee[2])
)

print("Sorted Employee Records:\n")

for employee in sorted_data:
    print(employee)

Sample Output

Sorted Employee Records:

('Rahul', 'HR', 45000)
('Neha', 'HR', 70000)
('Aman', 'IT', 50000)
('Priya', 'IT', 65000)
('Rohit', 'Sales', 42000)

Explanation

The lambda function returns a tuple containing the department and salary. Python sorts records by the first field and, if equal, by the second field.

Concepts Covered

  • Lambda Functions
  • Tuple Sorting
  • Multiple Sorting Keys
  • sorted()

19. Python Program to Find the Longest String Using Lambda

Problem Statement

Write a Python program to find the longest string in a list using a lambda function.

Python Solution

languages = [
    "Python",
    "Java",
    "JavaScript",
    "SQL",
    "C++",
    "TypeScript"
]

longest = max(
    languages,
    key=lambda language: len(language)
)

print("Longest String:", longest)

Sample Output

Longest String: TypeScript

Explanation

The lambda function returns the length of each string, allowing max() to identify the longest string.

Concepts Covered

  • Lambda Functions
  • max()
  • len()
  • String Processing

20. Python Program to Create a Price Calculator Using Lambda and map()

Problem Statement

Write a Python program to increase the price of every product by 18% GST using a lambda function and the map() function.

Python Solution

prices = [500, 1200, 2500, 800, 1500]

final_prices = list(
    map(
        lambda price: round(price * 1.18, 2),
        prices
    )
)

print("Prices After GST:")
print(final_prices)

Sample Output

Prices After GST:
[590.0, 1416.0, 2950.0, 944.0, 1770.0]

Explanation

The lambda function applies an 18% GST to each price. The map() function processes every element in the list and returns the updated prices.

Concepts Covered

  • Lambda Functions
  • map()
  • Arithmetic Operations
  • List Processing

21. Python Program to Find the Second Highest Salary Using Lambda

Problem Statement

Write a Python program to find the employee with the second highest salary from a list of dictionaries using a lambda function.

Python Solution

employees = [
    {"Name": "Rahul", "Salary": 45000},
    {"Name": "Priya", "Salary": 72000},
    {"Name": "Aman", "Salary": 58000},
    {"Name": "Neha", "Salary": 81000},
    {"Name": "Rohit", "Salary": 65000}
]

sorted_employees = sorted(
    employees,
    key=lambda employee: employee["Salary"],
    reverse=True
)

second_highest = sorted_employees[1]

print("Employee:", second_highest["Name"])
print("Salary:", second_highest["Salary"])

Sample Output

Employee: Priya
Salary: 72000

Explanation

The lambda function sorts employees by salary in descending order. The second element in the sorted list represents the employee with the second highest salary.

Concepts Covered

  • Lambda Functions
  • sorted()
  • Dictionary
  • Real-world Employee Data

22. Python Program to Group Words by Their First Letter Using Lambda

Problem Statement

Write a Python program to group words according to their first letter using a lambda function.

Python Solution

from itertools import groupby

words = [
    "Apple",
    "Ant",
    "Banana",
    "Ball",
    "Cat",
    "Car"
]

words.sort(key=lambda word: word[0])

groups = {
    key: list(group)
    for key, group in groupby(words, key=lambda word: word[0])
}

print(groups)

Sample Output

{
'A': ['Apple', 'Ant'],
'B': ['Ball', 'Banana'],
'C': ['Car', 'Cat']
}

Explanation

The list is first sorted by the initial letter. The groupby() function then groups consecutive words with the same starting character.

Concepts Covered

  • Lambda Functions
  • itertools.groupby()
  • Dictionary Comprehension
  • String Processing

23. Python Program to Find the Most Expensive Product Using Lambda

Problem Statement

Write a Python program to find the most expensive product from a nested dictionary using a lambda function.

Python Solution

products = {
    "Laptop": {"Price": 65000},
    "Mobile": {"Price": 30000},
    "Monitor": {"Price": 18000},
    "Keyboard": {"Price": 2500}
}

expensive = max(
    products.items(),
    key=lambda product: product[1]["Price"]
)

print("Most Expensive Product:", expensive[0])
print("Price:", expensive[1]["Price"])

Sample Output

Most Expensive Product: Laptop
Price: 65000

Explanation

The lambda function extracts the price from each nested dictionary, allowing max() to identify the product with the highest price.

Concepts Covered

  • Lambda Functions
  • Nested Dictionary
  • max()
  • Real-world Product Data

24. Python Program to Sort Students by Grade and Name Using Lambda

Problem Statement

Write a Python program to sort student records first by grade (descending) and then alphabetically by name using a lambda function.

Python Solution

students = [
    {"Name": "Rahul", "Grade": 85},
    {"Name": "Priya", "Grade": 92},
    {"Name": "Aman", "Grade": 92},
    {"Name": "Neha", "Grade": 78},
    {"Name": "Rohit", "Grade": 85}
]

sorted_students = sorted(
    students,
    key=lambda student: (-student["Grade"], student["Name"])
)

print("Sorted Student Records:\n")

for student in sorted_students:
    print(student)

Sample Output

Sorted Student Records:

{'Name': 'Aman', 'Grade': 92}
{'Name': 'Priya', 'Grade': 92}
{'Name': 'Rahul', 'Grade': 85}
{'Name': 'Rohit', 'Grade': 85}
{'Name': 'Neha', 'Grade': 78}

Explanation

The lambda function returns a tuple where the grade is negated to achieve descending order, while names are sorted alphabetically when grades are equal.

Concepts Covered

  • Lambda Functions
  • Multiple Sorting Keys
  • sorted()
  • Dictionary Sorting

25. Python Program to Build a Sales Report Using Lambda

Problem Statement

Write a Python program to calculate the total sales amount for each order using a lambda function and display the results.

Python Solution

orders = [
    {"Product": "Laptop", "Price": 55000, "Quantity": 2},
    {"Product": "Mouse", "Price": 800, "Quantity": 5},
    {"Product": "Keyboard", "Price": 1500, "Quantity": 3},
    {"Product": "Monitor", "Price": 18000, "Quantity": 2}
]

totals = list(
    map(
        lambda order: {
            "Product": order["Product"],
            "Total": order["Price"] * order["Quantity"]
        },
        orders
    )
)

print("Sales Report:\n")

for item in totals:
    print(item)

Sample Output

Sales Report:

{'Product': 'Laptop', 'Total': 110000}
{'Product': 'Mouse', 'Total': 4000}
{'Product': 'Keyboard', 'Total': 4500}
{'Product': 'Monitor', 'Total': 36000}

Explanation

The map() function applies a lambda expression to each order. The lambda calculates the total sales amount by multiplying the product price by its quantity and returns a new dictionary containing the product name and total amount.

Concepts Covered

  • Lambda Functions
  • map()
  • Nested Dictionary
  • Real-world Sales Report
  • Functional Programming

Frequently Asked Questions (FAQs)

1. What is a lambda function in Python?

A lambda function is a small anonymous (unnamed) function that can have any number of arguments but only one expression. It is commonly used for short operations where creating a full function using def is unnecessary.

Syntax:

lambda arguments: expression

Example:

square = lambda x: x ** 2

print(square(6))

Output

36

Concepts Covered

  • Lambda Function
  • Anonymous Function
  • Expression

2. What is the difference between a lambda function and a normal function?

Lambda FunctionNormal Function
Anonymous functionNamed function
Uses lambda keywordUses def keyword
Single expression onlyMultiple statements allowed
Automatically returns the resultUses the return statement
Best for short operationsBest for complex logic

Example:

# Lambda Function
multiply = lambda a, b: a * b

# Normal Function
def multiply_numbers(a, b):
    return a * b

print(multiply(5, 4))
print(multiply_numbers(5, 4))

3. Can a lambda function have multiple arguments?

Yes. A lambda function can accept any number of arguments, but it can contain only one expression.

Example:

average = lambda a, b, c: (a + b + c) / 3

print(average(80, 90, 100))

Output

90.0

4. Why are lambda functions called anonymous functions?

Lambda functions are called anonymous because they do not require a function name. They are often created and used immediately without being stored in a variable.

Example:

print((lambda x: x + 10)(20))

Output

30

5. Where are lambda functions commonly used?

Lambda functions are widely used with built-in Python functions such as:

  • map()
  • filter()
  • reduce()
  • sorted()
  • max()
  • min()

They are also frequently used in data analysis, automation, machine learning, and web development.

6. Can a lambda function contain loops or multiple statements?

No. Lambda functions can contain only a single expression. They cannot include loops, multiple statements, assignments, or control structures like for, while, or try.

For complex logic, use a normal function.

Incorrect Example

# Not Allowed

lambda x:
    if x > 10:
        return x

Correct Example

check = lambda x: "Greater" if x > 10 else "Smaller"

print(check(15))

7. What is the difference between map() and filter() with lambda?

  • map() transforms every element in an iterable.
  • filter() selects only the elements that satisfy a condition.

Example

numbers = [1, 2, 3, 4, 5]

square = list(map(lambda x: x ** 2, numbers))

even = list(filter(lambda x: x % 2 == 0, numbers))

print(square)
print(even)

Output

[1, 4, 9, 16, 25]
[2, 4]

8. What is reduce() in Python, and how does it work with lambda?

The reduce() function applies a lambda function cumulatively to the elements of an iterable, reducing them to a single value.

It is available in the functools module.

Example

from functools import reduce

numbers = [1, 2, 3, 4]

result = reduce(
    lambda x, y: x + y,
    numbers
)

print(result)

Output

10

9. Are lambda functions faster than normal functions?

No. Lambda functions are not inherently faster than functions created with def. Both are compiled similarly by Python.

The main advantage of lambda functions is concise syntax and improved readability for short, one-time operations.

Choose:

  • Lambda for simple expressions.
  • Normal functions for reusable or complex logic.

10. Why are lambda functions important for Python interviews and real-world projects?

Lambda functions are frequently asked about in Python interviews because they demonstrate your understanding of functional programming and Python’s built-in higher-order functions.

Common interview topics include:

  • Lambda expressions
  • map()
  • filter()
  • reduce()
  • Sorting using lambda
  • Anonymous functions
  • Functional programming concepts
  • Data transformation
  • Data filtering
  • Real-world data processing

Lambda functions are extensively used in Data Science, Machine Learning, Artificial Intelligence, Automation, Pandas, NumPy, ETL pipelines, Backend Development, and Web Applications. Learning them helps you write cleaner, more concise, and more Pythonic code while improving your problem-solving skills for coding interviews and production-level projects.

Chapter Summary

After completing this chapter, you have learned:

  • Lambda functions
  • Anonymous functions
  • Lambda with arguments
  • Conditional expressions
  • Lambda with sort()
  • Lambda with sorted()
  • Lambda with map()
  • Lambda with filter()
  • Real-world sorting using lambda
  • Writing concise Python functions

Written by Shubhranshu Shekhar, who has trained 20000+ students in coding.

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