In this tutorial we will learn about python filter method and its uses.

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.

 

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