Python map(): Apply a Function to Every Item in an Iterable

The map() function applies a given function to each item in an iterable (like a list or tuple) and returns a new iterable (map object). It’s useful for processing lists efficiently, transforming data, and applying functions without loops.

Example

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

This squares each number in the list.

Syntax

map(function, iterable)

function → A function that processes each item.
iterable → A list, tuple, or other sequence.
Returns → A map object (convert it to list() or tuple() to see results).

1. Doubling Each Number in a List

nums = [1, 2, 3, 4]
doubled = list(map(lambda x: x * 2, nums))
print(doubled)
# Output: [2, 4, 6, 8]

Transforms each number efficiently.

2. Converting Strings to Uppercase

words = ["hello", "world"]
uppercased = list(map(str.upper, words))
print(uppercased)
# Output: ['HELLO', 'WORLD']

Applies string methods to all elements.

3. Using `map()` with Multiple Lists

a = [1, 2, 3]
b = [4, 5, 6]

summed = list(map(lambda x, y: x + y, a, b))
print(summed)
# Output: [5, 7, 9]

Pairs up elements and processes them together.

4. Converting List Items to Integers

values = ["10", "20", "30"]
numbers = list(map(int, values))
print(numbers)
# Output: [10, 20, 30]

Useful for handling numeric input from users.

5. Removing Spaces from Strings

names = [" Alice ", " Bob ", "Charlie "]
cleaned = list(map(str.strip, names))
print(cleaned)
# Output: ['Alice', 'Bob', 'Charlie']

Cleans whitespace efficiently.

Key Notes

✔ Applies a function to every element in an iterable.
✔ Faster and more readable than loops.
✔ Can work with multiple iterables.
✔ Returns a map object—convert it to a list() or tuple() to view results.

By using map(), you can process large datasets efficiently, clean data, and transform lists with minimal code. 🚀