Python BasicsPython Basics11
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  1. 1Introduction to Python
  2. 2Python Hello World Program
  3. 3Python Comments
  4. 4Python Variables
  5. 5Python Constants
  6. 6Python Data Types
  7. 7Python Strings
  8. 8Python Type Conversions
  9. 9Python Basic Input and Output
  10. 10Python Operators
  11. 11Python Operator Precedence
Python Flow ControlPython Flow Control5
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  1. 1Python Conditional Statements
  2. 2Python Loops
  3. 3Python For Loop
  4. 4Python While Loop
  5. 5Python Break and Continue
Python CollectionsPython Collections5
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  1. 1Python Collections
  2. 2Python Lists
  3. 3Python Dictionaries
  4. 4Python Tuples
  5. 5Python Sets
Python FunctionsPython Functions4
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  1. 1Python Functions
  2. 2Python Functions with Parameters
  3. 3Python main() Function
  4. 4Python Lambda Functions
Python File HandlingPython File Handling1
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  1. 1Python File Operations
Python Exception HandlingPython Exception Handling3
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  1. 1Python Exceptions
  2. 2Python Exception Handling
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Python OOPsPython OOPs5
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  1. 1Python Object-Oriented Programming
  2. 2Python Inheritance
  3. 3Python Multiple Inheritance
  4. 4Python Encapsulation
  5. 5Python Polymorphism
Python Advanced ConceptsPython Advanced Concepts5
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  1. 1Python List Comprehension
  2. 2Python Iterators
  3. 3Python Generators
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Python LibrariesPython Libraries3
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  1. 1Python Email Tutorial
  2. 2Python JSON Tutorial
  3. 3Python datetime Tutorial
Python ReferencePython Reference2
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  1. 1Python Built-in Functions
  2. 2Python String Methods

Python map() Function – Apply a Function to Each Element

Python map() Function

The map() function lets you apply a function to each item in a list, tuple, or any other iterable — all in one line. It's a very handy tool for data transformation and functional programming.

Syntax

map(function, iterable)

Parameters:

  • function – A function to apply to each element of the iterable.
  • iterable – A sequence (like a list, tuple, or string) whose items you want to process.

Returns:

  • A map object (an iterator), which you can convert to a list or loop through.

Example: Square Numbers in a List

numbers = [1, 2, 3, 4]
squared = map(lambda x: x * x, numbers)
print(list(squared))
[1, 4, 9, 16]

Example: Convert Strings to Uppercase

words = ["apple", "banana", "cherry"]
uppercase_words = map(str.upper, words)
print(list(uppercase_words))
['APPLE', 'BANANA', 'CHERRY']

Use Case: Clean and Transform Data

Imagine you have a list of prices as strings and want to convert them to floats:

prices = ["10.5", "20.99", "5.00"]
prices_float = map(float, prices)
print(list(prices_float))
[10.5, 20.99, 5.0]

Using map() with Multiple Iterables

You can also use map() with two or more iterables:

a = [1, 2, 3]
b = [4, 5, 6]
sum_values = map(lambda x, y: x + y, a, b)
print(list(sum_values))
[5, 7, 9]

Common Mistakes

  • Forgetting to convert the map object: map() returns an iterator, not a list by default.
  • Not using a function: You must pass a valid function or lambda.
  • Mismatch in length: If using multiple iterables, map() stops at the shortest one.

Interview Tip

map() is often used to clean or transform datasets in one line. It shows functional programming skills and saves you from writing verbose for loops.

Summary

  • map() applies a function to each item of an iterable.
  • Returns a map object (an iterator).
  • Often used with lambda for quick transformations.
  • Works with multiple iterables too.

Practice Problem

Write a program that takes a list of numbers and returns a new list with the cube of each number using map().

nums = [2, 3, 4]
cubes = map(lambda x: x**3, nums)
print(list(cubes))