`map()` Function in Python [ English ]

`map()` Function in Python

1. Introduction

The map() function in Python is a built-in function used to apply a specified function to every element of an iterable (such as a list, tuple, or string). It returns an iterator containing the results after applying the function to each element.

The map() function is commonly used when the same operation needs to be performed on multiple elements of a sequence.

2. Syntax

map(function, iterable)

Parameters

function A function that defines the operation to be performed on each element.
iterable A sequence such as a list, tuple, or string whose elements will be processed.

Return Value

Returns a map object (iterator) containing the results of applying the function to each element.

3. Basic Example

def square(n):
    return n * n

numbers = [1, 2, 3, 4]

result = map(square, numbers)

print(list(result))

Output

[1, 4, 9, 16]

Explanation

The function square() is applied to every element of the list numbers.
map() returns an iterator containing the squared values.

4. Using `map()` with a Lambda Function

A lambda function is an anonymous function used for short operations.

numbers = [1, 2, 3, 4]

result = map(lambda x: x * 2, numbers)

print(list(result))

Output

[2, 4, 6, 8]

Explanation

The lambda function multiplies each number by 2.
map() applies this operation to every element.

5. Example with Multiple Iterables

map() can also take multiple iterables as arguments.

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

result = map(lambda x, y: x + y, a, b)

print(list(result))

Output

[5, 7, 9]

Explanation

The lambda function adds corresponding elements from lists a and b.

6. Example with String Conversion

numbers = [1, 2, 3, 4]

result = map(str, numbers)

print(list(result))

Output

['1', '2', '3', '4']

Explanation

The str() function converts each number into a string.

7. Without `map()` vs With `map()`

Without map()

numbers = [1, 2, 3]
result = []

for n in numbers:
    result.append(n * 2)

print(result)

With map()

numbers = [1, 2, 3]
result = map(lambda x: x * 2, numbers)

print(list(result))

Advantage

map() makes the code shorter and more efficient.

8. Important Points

map() does not return a list directly; it returns a map object (iterator).
To see the results, it is often converted into a list using list().

Example:

result = map(lambda x: x + 1, [1, 2, 3])
print(result)        # map object
print(list(result))  # actual values

9. Practical Example

prices = [100, 200, 300]

# Add 10% tax to each price
result = map(lambda x: x * 1.10, prices)

print(list(result))

Output

[110.0, 220.0, 330.0]

10. Summary

map() is a built-in Python function used to apply a function to every element of an iterable.
It returns a map object (iterator).
It can work with one or more iterable objects.
It is commonly used with lambda functions for short operations.
It helps make code shorter and more efficient.

Notes

`map()` Function in Python [ English ]

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