How to Use reverse() and reversed() in Python
In this tutorial, you'll learn how to use the reverse() list method and reversed() function in Python.
Python lists have a built-in method called reverse(). You can use it to reverse the elements of the list in place.
There is also a built-in function called reversed() in Python. Unlike reverse(), the reversed() function takes a sequence and returns a reverse iterator.
Python reverse() List Method
Python reverse() Syntax
The syntax of the reverse() list method is as follows:
list.reverse()
Python reverse() Examples
Reverse a List of Strings
The following code illustrates an example of reversing a list of strings:
companies = ["Microsoft", "Oracle", "Apple", "Facebook", "Twitter", "Yahoo"]
companies.reverse()
print (companies)
Output:
['Yahoo', 'Twitter', 'Facebook', 'Apple', 'Oracle', 'Microsoft']
Reverse a List of Numbers
The following code illustrates an example of reversing a list of numbers:
numbers = [100, 200, 300, 400, 500, 600, 700, 800, 900, 1000]
numbers.reverse()
print (numbers)
Output:
[1000, 900, 800, 700, 600, 500, 400, 300, 200, 100]
Python reversed() Function
Python reversed() Function Syntax
The syntax of the Python reversed() function is as follows:
reversed(sequence)
Python reversed() Parameter
- sequence: Required, and can be any iterable object, a list, tuple, set, or dictionary
Python revered() Function Examples
Reverse a List
The following code illustrates an example of how to reverse a list and loop over the returned reverse iterator:
companies = ["Microsoft", "Oracle", "Apple", "Facebook", "Twitter", "Yahoo"]
companies = reversed(companies)
for company in companies:
print (company)
Output:
Yahoo
Apple
Oracle
Microsoft
Reverse a Tuple
The following code reverses the elements of the tuple and uses the list constructor to create a list of strings from the reverse iterator:
fruits_tuple = ("Apple", "Melon", "Orange", "Watermelon", "Grapefruit", "Mango", "Kiwi")
fruits_list = list(reversed(fruits_tuple))
print (fruits_list)
Output:
['Kiwi', 'Mango', 'Grapefruit', 'Watermelon', 'Orange', 'Melon', 'Apple']
Reverse a List of Dictionaries
The following code reverses a list of dictionaries:
students = [
{"ID": "2001", "Name": "James"},
{"ID": "2002", "Name": "Roland"},
{"ID": "2003", "Name": "John"},
{"ID": "2004", "Name": "Josh"},]
iterator = reversed(students)
for i in iterator:
print ("ID:", i["ID"], " | " , "Name:", i["Name"])
Output:
ID: 2004 | Name: Josh
ID: 2003 | Name: John
ID: 2002 | Name: Roland
ID: 2001 | Name: James
In this tutorial, you learned the reverse() list method and reversed()function in Python.