Creating a New Dictionary from Two Existing Dictionaries in Python

Learn how to effectively merge a nested dictionary with a dictionary of lists in Python. This guide breaks down the process into simple steps for easy understanding. --- This video is based on the question https://stackoverflow.com/q/66068150/ asked by the user 'Fusdev' ( https://stackoverflow.com/u/14885707/ ) and on the answer https://stackoverflow.com/a/66068404/ provided by the user 'NickHilton' ( https://stackoverflow.com/u/6801991/ ) 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: Create a new dictionary from 2 existing dictionory (1 nested dictionory , 1 dictionory of lists) python 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. --- Merging Dictionaries in Python: A Step-by-Step Guide Dictionaries are incredibly powerful data structures in Python. They allow you to store and manage data in a way that's easy to access and modify. In this post, we will address a specific problem: how to create a new dictionary from two existing dictionaries, where one is a nested dictionary, and the other is a dictionary of lists. The Problem Imagine you have two dictionaries: K: A dictionary of lists. L: A nested dictionary. Here's what these dictionaries look like: K: [[See Video to Reveal this Text or Code Snippet]] L: [[See Video to Reveal this Text or Code Snippet]] Your Goal You want to create a new dictionary M such that: You check if the b values from dictionary L are present in the lists of dictionary K. If they are present, you create a new dictionary where each key corresponds to a key from K, and its value is a list of keys from L that have matching b values. Example Output For the given dictionaries, you expect an output like: [[See Video to Reveal this Text or Code Snippet]] The Solution Step 1: Create a Lookup for b Values The first step in solving this problem is to create an initial lookup from dictionary L. This allows us to quickly access the keys of L based on the b values. We will use a defaultdict which helps in storing values in a set to manage duplicated b values easily. [[See Video to Reveal this Text or Code Snippet]] Step 2: Build the Resulting Dictionary M Now that we have our lookup complete, we can iterate through dictionary K and match each value against our lookup. If a match is found, add the respective keys from L to dictionary M. [[See Video to Reveal this Text or Code Snippet]] Summary of the Code Combining everything, our code looks as follows: [[See Video to Reveal this Text or Code Snippet]] Conclusion By following these steps, you can effortlessly create a new dictionary from two existing dictionaries in Python. Utilizing Python's defaultdict allows for cleaner and more efficient code, particularly when handling potential duplicate values. This approach could easily be adapted to similar problems where you need to consolidate data from different sources. If you have any further questions or need additional examples, feel free to reach out in the comments below!