How to Read and Modify a Nested Dictionary in Python 3: A Recursive Approach

Описание: Learn how to effectively read each value in a nested dictionary and modify it using Python 3. This guide focuses on updating specific values through a recursive function.
---
This video is based on the question https://stackoverflow.com/q/66295672/ asked by the user 'Rafiq' ( https://stackoverflow.com/u/3600487/ ) and on the answer https://stackoverflow.com/a/66296014/ provided by the user 'Marco Luzzara' ( https://stackoverflow.com/u/5587393/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to read each of the values in a nested dictionary using Python 3 and create a similar dictionary after modifiying a value

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Read and Modify a Nested Dictionary in Python 3: A Recursive Approach

Nested dictionaries are a powerful feature in Python that allows for complex data structures, such as a mark sheet for students across different schools and grades. However, when it comes to reading and modifying these deeply nested structures, it can become challenging, especially if you want to avoid hardcoding your approach.

In this guide, we will explore a method to read through a nested dictionary, find values that meet specific criteria (in this case, grades lower than 90), and update them in an efficient and elegant way using recursion.

The Problem

Imagine a scenario where you have a nested dictionary representing students' marks across different grades and schools. Your goal is to find any grades that are lower than 90 in Grade2 and raise those grades to 90.

Example Input

Here’s a structured example of the nested dictionary we’re working with:

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

The goal is to transform this input into a new dictionary where the grades lower than 90 have been increased to 90.

Example Output

The expected output after modification would look like this:

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

The Solution

To achieve this modification efficiently, we can utilize a recursive function that navigates through the nested dictionary. Here’s how you can create such a function.

The Recursive Function

Let’s break down the recursive function that accomplishes this task:

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

Explanation of the Code

Loop Through the Dictionary: The for loop iterates over each key k in the dictionary sheet.

Check for Integer Values:

The first if statement checks whether the value associated with the key is an integer and if it’s below 90. If both conditions are met, it updates the score to 90.

Check for Nested Dictionaries:

The second if statement checks whether the value associated with the key is another dictionary. If true, it recursively calls transformMap() on that nested dictionary.

In-Place Modification

It's important to note that this function modifies the original dictionary in place without creating a new one. This is typically more memory efficient.

Conclusion

Using a recursive function to handle nested dictionaries makes your code both flexible and reusable. Instead of relying on multiple for loops and complicated conditions, this approach allows you to write cleaner code that can be adapted to any nested dictionary structure.

Next time you need to manipulate data stored in nested dictionaries, remember the power of recursion!