Simplifying String Filtering in Python: Removing Non-Decimal Values from Lists

Описание: Discover how to efficiently remove specific values from lists of strings in Python, simplifying your code without resorting to complex regex.
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This video is based on the question https://stackoverflow.com/q/72379767/ asked by the user 'João Pedro' ( https://stackoverflow.com/u/19198939/ ) and on the answer https://stackoverflow.com/a/72379850/ provided by the user 'Nathan' ( https://stackoverflow.com/u/5274764/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Simplifying String Filtering in Python: Removing Non-Decimal Values from Lists

Have you ever faced the challenge of filtering through a list of strings in Python, particularly when trying to remove specific values? If you've attempted to use regular expressions (regex) but found the process to be cumbersome and complex, you're not alone. Many programmers, regardless of experience level, may struggle with this task. In this guide, we will explore how to effectively remove all values from a list of strings that do not contain a decimal number represented with a comma (e.g., '34,79' or '135925,82').

The Challenge

Given the example below, we want to eliminate any strings in the list that do not fit the decimal format:

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The expected output from filtering such a list would give us:

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The Solution

Instead of relying on complex regex expressions, Python offers simpler alternatives that are more efficient and easier to read. One effective method is to use the in keyword alongside list comprehension.

List Comprehension

List comprehension is a powerful feature in Python that allows you to create a new list by applying an expression to each item in an existing list. Let's see how you can filter out values without using regex.

Here’s the straightforward approach:

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Breaking Down the Code

my_list: This is the original list of strings.

my_filtered_list: This variable stores the new list that will only contain strings with a comma (,) — indicating a decimal value.

[s for s in my_list if ',' in s]: This is the list comprehension that iterates through each string s in my_list and checks if a comma exists. If it does, s is included in my_filtered_list.

Creating a Function

To make this process reusable, you can define a function. Here’s how:

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How to Use the Function

Simply call your newly created function with any list you want to filter:

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Conclusion

This method not only simplifies your code but enhances its readability and performance. By using basic Python functionality rather than resorting to regex, you can efficiently filter out unwanted values from your lists of strings. With this knowledge, you can handle similar challenges in your coding projects with ease.

Don't hesitate to try implementing this in your own Python scripts! Happy coding!