How to Create a Custom Sorting Function for Dictionary Key Values in Python

Learn how to sort dictionary key values based on custom criteria in Python. This guide provides a step-by-step explanation for sorting keys accurately using specific characters.
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How to Create a Custom Sorting Function for Dictionary Key Values in Python

Sorting words or keys in a dictionary can sometimes be tricky, especially when you need to follow a certain order based on custom criteria. For example, you might have a dictionary where keys look like CC-1A, CC-1B, etc., and you want to sort them based on specific character locations. In this guide, we will walk through how to create a custom sorting function for the key values in your dictionary.

The Problem

Suppose you have a dictionary with keys that follow a pattern (for instance, CC-1A, CC-1B, SS-1A, etc.). These keys are stored in a random order, and you want to sort them in a specific sequence based on the following rules:

Sort first by the fourth character (which corresponds to a number, like 1, 3, etc.)

Sort second by the last character (like A, B, etc.)

Sort finally by the first two characters (for example, CC, SS)

Example Dictionary

Let's say you have the following list of keys to work with:

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The Solution

To implement a custom sorting function, we can use Python’s sorting capabilities along with a lambda function that allows us to specify the exact order in which we want the keys sorted.

Step-by-Step Guide

Create the Dictionary: First up, we’ll create the dictionary using your list of keys. Here is how you can set up your dictionary and values associated with your keys:

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

Sort the Dictionary: Next, apply the sorting using a custom key via a lambda function. This function will take into account the positional characters that we identified earlier:

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

x[3] refers to the fourth character in the keys.

x[-1] retrieves the last character.

x[:2] gives the first two characters of each key.

Display the Sorted Result: Finally, print out the sorted dictionary items:

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

Putting It All Together

Here’s the complete code in one place:

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Expected Output

You will see output that accurately reflects your desired sort order:

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

Conclusion

Sorting dictionary keys based on custom criteria can enhance the organization of your data. With Python, it's quite straightforward to create a custom function that allows you to specify the exact sorting order you need. Using the method presented in this guide, you can adapt it to various scenarios where dictionary key sorting is necessary. Happy coding!