The map () function in Python

The map () function built into Python works to browse all the elements of an iterable (list, tuple, dictionary .) through a given function and returns a list of results after execution.

So the syntax of the map () function like, what parameters it has and how to use it? Invites you to read the track.

Syntax of map () function in Python

 map(function, iterable, .) 

The parameters of the map () function

1. function The function executes for each element in the iterable.
2. iterable : a list, tuple, dictionary . want to browse.

You can pass multiple iterablecho map () functions.

Return value from map ()

The map () function browses all iterable elements through the function and returns a list of results after execution.

The value returned from map () is called map object. This object can be passed to list () functions (to create lists in Python), or set () (to create a new set of elements) .

Example 1: How does map () work?

 def binhphuong(n): return n*n # viet boi TipsMake.com number = (25, 100, 225, 400) ketqua = map(binhphuong, number) # chuyen map object thanh list print(list(ketqua)) 

When you run the program, the output will be:

 [25, 100, 225, 400] 

In the above example, every element in the original tuple is square.

Example 2: How to use lambda functions with map ()

Because map () always needs parameters to pass, lambda functions are often used with map ().

In Python, lambda functions or anonymous functions are defined without a name. If normal functions are defined using the keyword def , then anonymous functions are defined using the keyword lambda .

Read more: Anonymous functions, Lambda in Python.

 # viet boi TipsMake.com number = (5, 10, 15, 20) result = map(lambda x: x*x, number) # chuyen map object thanh list sobinhphuong = list(result) print(sobinhphuong) 

Running the program, the result is returned:

 [25, 100, 225, 400] 

The result is no different from example 1 .

Example 3: Passing multiple iterator parameters to map () using lambda

In this example, the corresponding elements of the two lists are added.

 num1 = [4, 5, 6] num2 = [5, 6, 7] result = map(lambda n1, n2: n1+n2, num1, num2) print(list(result)) 

The result is:

 [9, 11, 13] 

See also: Python built-in functions