How to create Python map() function

map() function returns a map object(which is an iterator) of the results after applying the given function to each item of a given iterable (list, tuple etc.)

Syntax :

map(fun, iter)

Parameters :

fun : It is a function to which map passes each element of given iterable.
iter : It is a iterable which is to be mapped.

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

Returns :

Returns a list of the results after applying the given function  
to each item of a given iterable (list, tuple etc.)

NOTE : The returned value from map() (map object) then can be passed to functions like list() (to create a list), set() (to create a set) .

CODE 1

# Python program to demonstrate working
# of map.
  
# Return double of n
def addition(n):
    return n + n
  
# We double all numbers using map()
numbers = (1, 2, 3, 4)
result = map(addition, numbers)
print(list(result))

Output :

[2, 4, 6, 8]

CODE 2
We can also use lambda expressions with map to achieve above result.

# Double all numbers using map and lambda
  
numbers = (1, 2, 3, 4)
result = map(lambda x: x + x, numbers)
print(list(result))

Output :

[2, 4, 6, 8]

CODE 3

# Add two lists using map and lambda
  
numbers1 = [1, 2, 3]
numbers2 = [4, 5, 6]
  
result = map(lambda x, y: x + y, numbers1, numbers2)
print(list(result))

Output :

[5, 7, 9]

CODE 4

# List of strings
l = ['sat', 'bat', 'cat', 'mat']
  
# map() can listify the list of strings individually
test = list(map(list, l))
print(test)

Output :

[['s', 'a', 't'], ['b', 'a', 't'], ['c', 'a', 't'], ['m', 'a', 't']]

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