Map and Filter function in Python

Welcome to the tutorial of Python

In this tutorial we will try to understand the powerful Map and Filter function


1) map() function - It returns a list of the results after applying the given function to each item of a given iterable (list, tuple etc.) 

Syntax : map( function, iteration ) ;
               where, 
                      function = It is a function to which map passes each element of given iterable.
                      iteration = It is a iterable which is to be mapped.


NOTE : You can pass one or more iterable to the map() function.

Conventional Method	Map Function Advantage
Def times2(var):         Return var*2 Seq = [1,2,3,4,5] Out = [] For num in seq:        Out.append(times2(num))	Def times2(var):         Return var*2 Seq = [1,2,3,4,5] Out = list(map(times2,seq))

2) Filter function - The filter() method filters the given sequence with the help of a function that tests each element in the sequence to be true or not. It uses lambda function.

Syntax : filter(lambda num: num%2==0, seq)

Eg: Print all words starting with s in the sequence 
        seq = ['sa','sb','df','rf','sz']

Ans : list(filter(lambda word: word[0] == 's', seq))