Python filter() Method

What is Python filter() Method?

The filter() method returns an iterator where the items are filtered through a method to test if the item is true or not.

The syntax of filter() method is:

filter(method, iterable)

Python filter() Method Parameters

filter() method takes two parameters:

• method - it will take a method that tests if elements of an iterable return true or false.
• iterable - iterable which will be filtered, can be sets, lists, tuples, or containers of any iterators

Let us see some examples of filter() method.

Example 1: How filter() method works for the iterable list?

# list of letters
letters = ['a', 'b', 'd', 'e', 'i', 'j', 'o']

# function that filters vowels
def filter_vowels(letter):
    vowels = ['a', 'e', 'i', 'o', 'u']

    if(letter in vowels):
        return True
    else:
        return False

filtered_vowels = filter(filter_vowels, letters)

print('The filtered vowels are:')
for vowel in filtered_vowels:
    print(vowel)

The output will be as follow:

The filtered vowels are:
a
e
i
o

Rules of filter() method

filter() method can take only an iterator as an input which can be passed in method to check for each element in the iterable.