Skip to content

Python | sort list of tuple based on sum

Python - Sort list of list by specified index

Last Updated : 18 Dec, 2024

When working with a list of lists, we often need to sort the inner lists based on the values at a specific index. Sorting by a specified index is useful in the custom ordering of multidimensional data. In this article, we will explore different ways to sort a list of lists by a specified index in Python.

Using `sorted()`

The most simple and efficient way to sort a list of lists by a specified index is using the sorted() function with a key. It is efficient and concise for sorting by any index.

Python

a = [[1, 'Python', 50], [2, 'with', 30], [3, 'GFG', 40]]  # Sorting by the 2nd index  b = sorted(a, key=lambda x: x[2]) print(b)

Output

[[2, 'with', 30], [3, 'GFG', 40], [1, 'Python', 50]]

Explanation:

The sorted() function sorts the list of lists a based on the 3rd element (x[2]) of each sublist, as specified in the key argument using a lambda function.
The output is a new list where sublists are ordered by their price values (the 3rd element). The original list remains unchanged.

Let's explore some other methods to check how we can sort list of list by specified index.

Table of Content

Using `itemgetter()`

Using itemgetter() from the operator module is an efficient way to retrieve elements at specific indices in a list or other iterable.

Python

from operator import itemgetter  a = [[1, 'Python', 50], [2, 'is', 30], [3, 'fun!', 40]]  # Sorting by the 2nd index b = sorted(a, key=itemgetter(2)) print(b)

Output

[[2, 'is', 30], [3, 'fun!', 40], [1, 'Python', 50]]

Explanation:

itemgetter(2) fetches the value at the specified index.
This method is often more efficient than using a lambda function, especially with large datasets, as it avoids using lambda.

Using `list.sort()`

list.sort() method is used to sort a list in place, meaning it rearranges the elements of the list without creating a new list.

Python

a = [[1, 'Python', 50], [2, 'is', 30], [3, 'fun!', 40]]  # Sorting in place by the 2nd index a.sort(key=lambda x: x[2]) print(a)

Output

[[2, 'is', 30], [3, 'fun!', 40], [1, 'Python', 50]]

Explanation:

sort() method modifies the list data in place, arranging its sublists by the 3rd element (x[2]) as defined in the key argument using a lambda function.
Unlike sorted(), this does not create a new list but directly updates the original list, saving memory.

Sorting by Multiple Indices

Sometimes, we may want to sort a list by multiple indices in hierarchical order. It is useful for sorting data with ties at the first index.

Python

a = [[1, 'Python', 50], [2, 'is', 30], [3, 'fun!', 40]]  # Sorting by 2nd index first, then by 0th index sorted_data = sorted(a, key=lambda x: (x[1], x[0])) print(sorted_data)

Output

[[1, 'Python', 50], [3, 'fun!', 40], [2, 'is', 30]]

Explanation:

The key=lambda x: (x[1], x[0]) is a tuple that allows for multi-level sorting. Python compares tuples element by element, so it first sorts by the second element and resolves ties by the first element.

Python | sort list of tuple based on sum

manjeet_04

Improve

Article Tags :

Practice Tags :

Similar Reads

Python - Returning index of a sorted list

We are given a list we need to return the index of a element in a sorted list. For example, we are having a list li = [1, 2, 4, 5, 6] we need to find the index of element 4 so that it should return the index which is 2 in this case. Using bisect_left from bisect modulebisect_left() function from bis

Python - Get list of files in directory sorted by size

In this article, we will be looking at the different approaches to get the list of the files in the given directory in the sorted order of size in the Python programming language. The two different approaches to get the list of files in a directory are sorted by size is as follows: Using os.listdir(

Python | sort list of tuple based on sum

Given, a list of tuple, the task is to sort the list of tuples based on the sum of elements in the tuple. Examples: Input: [(4, 5), (2, 3), (6, 7), (2, 8)] Output: [(2, 3), (4, 5), (2, 8), (6, 7)] Input: [(3, 4), (7, 8), (6, 5)] Output: [(3, 4), (6, 5), (7, 8)] # Method 1: Using bubble sort Using th

Check if a List is Sorted or not - Python

We are given a list of numbers and our task is to check whether the list is sorted in increasing or decreasing order. For example, if the input is [1, 2, 3, 4], the output should be True, but for [3, 1, 2], it should be False. Using all()all() function checks if every pair of consecutive elements in

Creating a Sorted Merged List of Two Unsorted Lists in Python

Creating a sorted merged list of two unsorted lists involves combining the elements of both lists and sorting the resulting list in ascending order. For example: If we have list1 = [25, 18, 9] and list2 = [45, 3, 32] the output will be [3, 9, 18, 25, 32, 45]. Using + OperatorThis method merges the t

Internal working of list in Python

Introduction to Python lists :Â Python lists are internally represented as arrays. The idea used is similar to implementation of vectors in C++ or ArrayList in Java. The costly operations are inserting and deleting items near the beginning (as everything has to be moved). Insert at the end also becom

Python List index() - Find Index of Item

index() method in Python is a helpful tool when you want to find the position of a specific item in a list. It works by searching through the list from the beginning and returning the index (position) of the first occurrence of the element you're looking for. Example: [GFGTABS] Python a = ["cat

Python | Sort a tuple by its float element

In this article, we will see how we can sort a tuple (consisting of float elements) using its float elements. Here we will see how to do this by using the built-in method sorted() and how can this be done using in place method of sorting. Examples: Input : tuple = [('lucky', '18.265'), ('nikhil', '1

Sort a list of objects by multiple attributes in Python

In this article, we are going to learn how to sort a list by multiple attributes with Python. Introduction Python is a dynamically typed language that offers numerous data types, such as list, tuple, set, dictionary, etc. and sorting is the most commonly used operation on any data structures such as

Sort a List According to the Length of the Elements - Python

We are given a list of strings and our task is to sort the list based on the length of each string. For example, if the input is ["Python", "C", "Java", "JavaScript", "Go"], the output should be ["C", "Go", "Java", "Python", "JavaScript"] since shorter strings come first. Using sorted() sorted() fun