Skip to content

How to use Python filter()

FULL-STACK WEB DEVELOPMENT BOOTCAMP

2024 COHORT SIGNUPS END TOMORROW

Python provides 3 useful global functions we can use to work with collections: map(), filter() and reduce().

Tip: sometimes list comprehensions make more sense and are generally considered more pythonic

filter() takes an iterable and returns a filter object, which is another iterable, but without some of the original items.

You do so by returning True or False from the filtering function:

numbers = [1, 2, 3]

def isEven(n):
    return n % 2 == 0

result = filter(isEven, numbers)

print(list(result)) # [2]

You can use a lambda function to make the code more concise:

numbers = [1, 2, 3]

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

print(list(result)) # [2]
  • Learn modern web development in my BOOTCAMP (SIGNUP END TOMORROW FEB 20, 2024)
  • THE VALLEY OF CODE (+ PRO), your web development manual
  • I wrote 15+ coding BOOKS, all available in THE VALLEY OF CODE PRO
  • Indie solopreneur internet business masterclass SOLO LAB (summer 2024)