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Learn how to append the last items from one nested list to another based on a shared condition using simple Python techniques.
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Efficiently Merge Nested Lists in Python Based on Conditions

Working with nested lists in Python can be a bit tricky, especially when you need to combine data from two lists based on specific conditions. In this guide, we will explore a problem where we want to append the last element of one list to another, based on a matching first element in their inner lists.

The Problem

Suppose you are given two lists of lists:

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

The goal is to add the last elements from any of the nested lists in b to the corresponding nested lists in a, but only if their first elements match. For example:

The first elements in the nested lists of a and b are 1 (from a[0] and b[0]) and 4 (from a[1] and b[1]).

We want to append 9 from the first list in b to the first list in a, and 11 from the second list in b to the second list in a.

Ultimately, we want the final version of a to look like this:

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

The Solution

To achieve this, we will write a simple Python loop that checks the first elements of each pair of nested lists and appends the last element from b to a when the condition is met. Here's how you can do it:

Step-by-Step Breakdown

Loop Through Lists: Use a loop to go through each nested list of a and b.

Condition Check: For each iteration, check if the first elements of the current nested lists in a and b are equal.

Append the Last Element: If the first elements match, append the last element of the nested list from b to the corresponding list in a.

Sample Code

Here’s how you can implement this in Python:

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

Output

When you run this code, the output will be:

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

Conclusion

By following this straightforward approach, you can easily manipulate nested lists in Python based on specific conditions. This can be particularly useful in data processing tasks where lists represent related datasets. Remember, always ensure that your input lists are of the same length to avoid index errors.

Feel free to adapt this code to solve similar problems or to add more conditions based on your specific requirements.

Now that you know how to append last elements from nested lists in Python, what other challenges would you like to tackle? Let's keep coding!