Lambda and filter in Python Examples

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.

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# 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) 

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Output:

[65, 39, 221]

Given a list of strings, find all palindromes.

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# 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
result = list(filter(lambda x: (x == "".join(reversed(x))), my_list)) 
  
# printing the result
print(result) 

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Output :

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

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

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# 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
result = list(filter(lambda x: (Counter(str) == Counter(x)), my_list)) 
  
# printing the result
print(result) 

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Output :

['geeks', 'keegs']


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