Lambda and filter in Python Examples

Last Updated : 09 Jul, 2021

Prerequisite : Lambda in Python

Given a list of numbers, find all numbers divisible by 13.

Input : my_list = [12, 65, 54, 39, 102, 
                     339, 221, 50, 70]
Output : [65, 39, 221]

We can use Lambda function inside the filter() built-in function to find all the numbers divisible by 13 in the list. In Python, anonymous function means that a function is without a name.

The filter() function in Python takes in a function and a list as arguments. This offers an elegant way to filter out all the elements of a sequence “sequence”, for which the function returns True.

# Python Program to find numbers divisible  
# by thirteen from a list using anonymous  
# function 
  
# Take a list of numbers.  
my_list = [12, 65, 54, 39, 102, 339, 221, 50, 70, ] 
  
# use anonymous function to filter and comparing  
# if divisible or not 
result = list(filter(lambda x: (x % 13 == 0), my_list))  
  
# printing the result 
print(result)  

Output:

[65, 39, 221]

Given a list of strings, find all palindromes.

# Python Program to find palindromes in  
# a list of strings. 
  
my_list = ["geeks", "geeg", "keek", "practice", "aa"] 
  
# use anonymous function to filter palindromes. 
# Please refer below article for details of reversed 
# https://www.geeksforgeeks.org/reverse-string-python-5-different-ways/ 
result = list(filter(lambda x: (x == "".join(reversed(x))), my_list))  
  
# printing the result 
print(result)  

Output :

['geeg', 'keek', 'aa']

Given a list of strings and a string str, print all anagrams of str

# Python Program to find all anagrams of str in  
# a list of strings. 
from collections import Counter 
  
my_list = ["geeks", "geeg", "keegs", "practice", "aa"] 
str = "eegsk"
  
# use anonymous function to filter anagrams of x. 
# Please refer below article for details of reversed 
# https://www.geeksforgeeks.org/anagram-checking-python-collections-counter/ 
result = list(filter(lambda x: (Counter(str) == Counter(x)), my_list))  
  
# printing the result 
print(result)  

Output :

['geeks', 'keegs']

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Pushpanjali chauhan

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