Скачать или смотреть How to Use key in the Sort Function in Python

Discover how to effectively use the `key` parameter in Python's sort function to sort lists of tuples by numerical values instead of alphabetical order.
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Sorting a List of Tuples in Python

When working with lists in Python, you may find yourself needing to sort data in a specific order. One common scenario involves sorting a list of tuples, where each tuple contains both a string and a number. In this guide, we will explore how to sort such lists using the key parameter in the sort function.

The Problem

Consider the following list of tuples:

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If you want to sort this list by the numerical values (the second element in each tuple), you might be tempted to use the built-in sort() method like so:

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

However, simply calling sort() on the list will sort the tuples alphabetically by the first element, yielding the output:

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What you really want is to sort the list based on the second element (the number) and achieve an output that looks like this:

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

The Solution

To achieve this desired output, you can use the key parameter in the sort() method. Specifically, you can pass a lambda function to the key parameter that extracts the second value from each tuple.

Here’s how you can do it:

Step-by-Step Instructions

Define your list of tuples:

Start with your original list:

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Use the sort() method with a key:

Use the sort() method and pass a lambda function as the key:

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This lambda function takes a tuple (val) and returns the second element (val[1]), which is the numerical value you want to sort by.

Check the sorted list:

After calling sort(), your sorted list will look like this:

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

Conclusion

Using the key parameter in Python’s sort function allows for flexible and powerful sorting options. By applying a lambda function that targets specific elements within your data structure, you can control how your lists are sorted efficiently.

Now you have the tools to tackle sorting lists of tuples by numerical values rather than alphabetical order. Happy coding!