📘 Lesson · Lesson 81

Map, Filter, Reduce

Functional Tools

💡 At a Glance

map, filter and reduce apply a function to a whole list without writing loops — often used with lambda.

Python

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

[1, 4, 9, 16]

Python

nums = [1, 2, 3, 4, 5, 6]
even = list(filter(lambda x: x % 2 == 0, nums))
print(even)

[2, 4, 6]

Python

from functools import reduce
nums = [1, 2, 3, 4]
total = reduce(lambda a, b: a + b, nums)
print(total)

map transforms each item, filter keeps matching items, reduce combines to one value.
Often paired with lambda for short functions.

💡 एक नज़र में

map, filter और reduce पूरी list पर function लगाते हैं बिना loops लिखे — अक्सर lambda के साथ।

Python

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

[1, 4, 9, 16]

Python

nums = [1, 2, 3, 4, 5, 6]
even = list(filter(lambda x: x % 2 == 0, nums))
print(even)

[2, 4, 6]

Python

from functools import reduce
nums = [1, 2, 3, 4]
total = reduce(lambda a, b: a + b, nums)
print(total)