Overview

The map(), filter() and reduce() functions bring a bit of functional programming to Python. All three of these are convenience functions that can be replaced with List comprehensions or loops but provide a more elegant and short-hand approach to some problems

map() function

The map() function iterates through all items in the given iterable and executes the functions we passed as an argument on each of them.

Syntax

map(function, iterable(s))

Example

def starts_with_A(s):
	return s[0] == "A"

fruit = ["Apple", "Banana", "Pear", "Apricot", "Orange"]

map_object = map(starts_with_A, fruit)
print(list(map_object))

Output:

[True, False, False, True, False]

As we can see, we ended up with a new list where the function starts_with_A() was evaluated for each of the elements in the list fruit. The results of this function were added to the list sequentially.

The same can be done by the lambda function

fruit = ["Apple", "Banana", "Pear", "Apricot", "Orange"]
map_object = map(lambda s : s[0] == "A", fruit)
print(list(map_object))