How to Group Elements from a Nested List in Python by Three

Learn how to transform your nested list into a new format grouped by `three` elements, using simple Python code techniques.
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Grouping Elements from a Nested List in Python by Three

When working with nested lists in Python, there are times when you need to reorganize or manipulate the data. One such common requirement is to group elements from a nested list by a certain number — in this case, by three elements. In this guide, we will walk you through a practical example of how to achieve this, using both loops and list comprehensions.

Understanding the Problem

Let’s start with our initial nested list, which is structured in sub-lists:

[[See Video to Reveal this Text or Code Snippet]]

The goal is to create a new list where the elements are grouped by three, starting from every third index. This means that the desired output should look like this:

[[See Video to Reveal this Text or Code Snippet]]

Implementing the Solution

To achieve this, we will use a nested loop structure. The outer loop will iterate through the indices of the elements in steps of three, while the inner loop will gather the elements from each sub-list.

Step-by-Step Solution

Initialize a New List: We need a new list to store our grouped elements.

[[See Video to Reveal this Text or Code Snippet]]

Outer Loop: This loop will iterate through the indices of the inner lists with a step of three.

[[See Video to Reveal this Text or Code Snippet]]

Inner List: For each iteration of the outer loop, initialize an inner list to collect elements.

[[See Video to Reveal this Text or Code Snippet]]

Inner Loop for Rows: We will now iterate over the rows of starting_list for each group of three elements.

[[See Video to Reveal this Text or Code Snippet]]

Append to New List: After collecting the three elements from each row, append the inner list to new_lst.

[[See Video to Reveal this Text or Code Snippet]]

Complete Code

Here’s the complete code for the solution:

[[See Video to Reveal this Text or Code Snippet]]

Output

After running the above code, you will get:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Grouping elements from a nested list can seem challenging at first, but by breaking it down into manageable steps, you can simplify the process significantly. Whether using loops or list comprehensions, Python provides flexible tools to manipulate lists efficiently.

Feel free to try out this code and modify it according to your needs. Happy coding!