Скачать или смотреть How to Combine Duplicate Keys in a Dictionary and Calculate Their Averages in Python

Discover how to manage duplicate keys in a Python dictionary by combining their values and calculating averages. This step-by-step guide covers everything you need to know!
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How to Combine Duplicate Keys in a Dictionary and Calculate Their Averages in Python

When working with dictionaries in Python, you might encounter a situation where there are duplicate keys associated with different values. This can be particularly common when collecting data from different sources. The challenge then becomes, how do you manage those duplicates, combine their values, and in this case, calculate their averages? In this guide, we'll explore how to achieve just that.

Understanding the Problem

Let's say you have the following data structure in your Python code:

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Here, the movies list consists of tuples, where the first element is a key (like a movie identifier) and the second is a corresponding value (like a rating). Notice that the keys 'x' and 'y' appear multiple times, indicating we need a solution for these duplicates.

Expected Output

The objective is to combine these duplicate keys and compute their average values. The desired final dictionary looks like this:

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This represents the following calculations:

For key x: (57 + 22) / 2 = 39.5

For key y: (23 + 10 + 12) / 3 = 15

For key z: remains as 12 since there's only one occurrence

Step-by-Step Solution

To solve this problem, we can break down our solution into a few clear steps. Here’s how you can do it without any additional module imports, just using built-in Python functionalities.

Step 1: Initialize Your Data Structure

Start by preparing your data. In this case, we will keep using the movies list as provided:

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Step 2: Combine Values with a Dictionary

We'll create a new dictionary to store the keys and their associated values as lists. The setdefault method helps us append multiple values for a single key:

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At this point, md will look like:

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Step 3: Calculate Averages

Next, we will iterate over the dictionary to compute the average for each key. If a key has only one value, it remains unchanged. This can be implemented in one line of code:

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After this step, the final dictionary md will look like:

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Step 4: Output the Result

Finally, we can print the final dictionary to see the results:

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The output will be:

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Conclusion

In this guide, we tackled the challenge of managing duplicate keys in a Python dictionary. We learned how to combine their values and compute the average efficiently using built-in dictionary methods and comprehensions. This approach is straightforward and keeps our code clean without requiring any external libraries.

By mastering how to deal with duplicates in dictionaries, you can streamline data manipulation in Python and enhance your programming skills. Happy coding!