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Python filter() Function with Examples
Learn about the filter() function, its usages, syntax, and examples.
Submitted by IncludeHelp, on March 07, 2022
In Python programming language, the filter() function is a built-in function that is used to filter the given sequence (sets, lists, tuples, etc.) with the help of a function that checks each element in the given sequence to be true or not.
Syntax of filter() function
filter(function, sequence)
Here,
- function : A function that is used to check each element of the sequence whether true or not.
- sequence : A sequence like sets, lists, tuples, etc., needs to be filtered.
Return value of filter() function
It returns an iterator of filtered elements.
Python filter() Function (Example 1)
# Python program to demonstrate the
# example of filter() function
# Function to filter vowels from the sequence
def filterVowels(s):
vowels = ['a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U']
if (s in vowels):
return True
else:
return False
# Defining a sequence
seq = ['H', 'e', 'l', 'l', 'o', ' ', 'W', 'o', 'r', 'l', 'd']
# Filtering the vowels using filter() function
result = filter(filterVowels, seq)
print('The result is:')
for s in result:
print(s)
Output:
The result is:
e
o
o
Python filter() Function (Example 2)
The filter() function is normally used with the lambda functions to filter the elements of a sequence like sets, lists, tuples, or containers of any iterators.
# Python program to demonstrate the
# example of filter() function
# list of integers
fibo = [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
print("Original List :",fibo)
# filter even numbers using
# filter() and lambda
even = list(filter(lambda n:n%2==0,fibo))
print("Even List :",even)
Output:
Original List : [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
Even List : [0, 2, 8, 34]
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