Convert Set of Tuples to a List of Lists in Python

Python – Ways to sum list of lists and return sum list

Last Updated : 18 Dec, 2024

When working with nested lists (lists of lists), we may need to compute the sum of corresponding elements across all inner lists. In this article, we will see how Python provides multiple methods to perform this task. The most common and efficient way to sum up a list of lists is by using zip() combined list comprehension.

Python

a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

b = [sum(x) for x in zip(*a)]
print(b)

Output

[12, 15, 18]

zip(*lists) unpacks the inner lists and groups their corresponding elements together: [(1, 4, 7), (2, 5, 8), (3, 6, 9)].
sum(x) computes the sum of each tuple.
The result is a list containing the sum of corresponding elements: [12, 15, 18].

Let’s explore some other methods and see different ways to sum list of lists and return sum list in Python.

Table of Content

Using map() and sum()
Using NumPy
Using Loops

Using `map()` and `sum()`

map() function can be used to apply sum() to each group of corresponding elements.

Python

a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

b = list(map(sum, zip(*a)))
print(b)

Output

[12, 15, 18]

Explanation:

zip(*lists) groups corresponding elements across all lists.
map(sum, ...) applies the sum() function to each group.
list() converts the result back to a list.

Using N`umPy`

If we are working with large lists or require more advanced numerical operations, NumPy is a powerful library for such tasks.

Python

import numpy as np

a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
b = np.sum(a, axis=0).tolist()
print(b)

Output

[12, 15, 18]

Explanation:

np.sum() computes the sum along the specified axis.
axis=0 sums across the rows (corresponding elements).
.tolist() converts the result back to a Python list.

Using Loops

For a more manual approach, we can iterate through the lists using a for loop and sum the corresponding elements.

Python

a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

# Initialize a result list with zeros
b = [0] * len(a[0])

# Add elements from each list
for l in a:
    for i in range(len(l)):
        b[i] += l[i]

print(b)

Output

[12, 15, 18]

Explanation:

A result list sum_list is initialized with zeros.
A nested loop iterates through each list and its elements, adding corresponding values.

Convert Set of Tuples to a List of Lists in Python

garg_ak0109

Improve

Article Tags :

Practice Tags :

Similar Reads

Python | Ways to sum list of lists and return sum list

When working with nested lists (lists of lists), we may need to compute the sum of corresponding elements across all inner lists. In this article, we will see how Python provides multiple methods to perform this task. The most common and efficient way to sum up a list of lists is by using zip() comb

Convert Set of Tuples to a List of Lists in Python

Sets and lists are two basic data structures in programming that have distinct uses. It is sometimes necessary to transform a collection of tuples into a list of lists. Each tuple is converted into a list throughout this procedure, and these lists are subsequently compiled into a single, bigger list

How to Zip two lists of lists in Python?

zip() function typically aggregates values from containers. However, there are cases where we need to merge multiple lists of lists. In this article, we will explore various efficient approaches to Zip two lists of lists in Python. List Comprehension provides a concise way to zip two lists of lists

Python | Convert list of tuples to list of list

Converting list of tuples to list of lists in Python is a task where each tuple is transformed into list while preserving its elements. This operation is commonly used when we need to modify or work with the data in list format instead of tuples. Using numpyNumPy makes it easy to convert a list of t

Python - Get sum of last K list items using slice

Accessing elements in a list has many types and variations. These are an essential part of Python programming and one must have the knowledge to perform the same. This article discusses ways to fetch the last K elements and do its summation. Letâ€™s discuss certain solution to perform this task. Metho

Appending To One List In A List Of Lists

in a list in Python can be achieved using various methods, each with its own advantages. Choose the approach that best fits your specific requirements Lists of lists, also known as nested lists, are a powerful data structure in programming that allow for the organization of data in a hierarchical ma

Python - Summation of float string list

Sometimes, while working with Python list, we can have a problem in which we need to find summation in list. But sometimes, we donâ€™t have a natural number but a floating-point number in string format. This problem can occur while working with data, both in web development and Data Science domain. Le

Python - Convert List of Integers to a List of Strings

We are given a list of integers and our task is to convert each integer into its string representation. For example, if we have a list like [1, 2, 3] then the output should be ['1', '2', '3']. In Python, there are multiple ways to do this efficiently, some of them are: using functions like map(), re

Python - List of dictionaries all values Summation

Given a list of dictionaries, extract all the values summation. Input : test_list = [{"Apple" : 2, "Mango" : 2, "Grapes" : 2}, {"Apple" : 2, "Mango" : 2, "Grapes" : 2}] Output : 12 Explanation : 2 + 2 +...(6-times) = 12, sum of all values. Input : test_list = [{"Apple" : 3, "Mango" : 2, "Grapes" : 2

Python | Summation of dictionary list values

Sometimes, while working with Python dictionaries, we can have its values as lists. In this can, we can have a problem in that we just require the count of elements in those lists as a whole. This can be a problem in Data Science in which we need to get total records in observations. Let's discuss c