Скачать или смотреть Effective Techniques to Filter Out File Names in Python Using Regex and Native Functions

Learn how to efficiently bypass unwanted file names in Python by mastering regex patterns and filtering techniques.
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Minimizing File Name Selection in Python: Techniques for Filtering

Working with file names can sometimes present challenges, especially when you need to exclude certain patterns from your dataset. If you've found yourself in the position of wanting to filter out specific files based on their names in Python, you’re not alone! Many developers need to process large sets of files while ensuring they only work with relevant ones. In this guide, we'll explore how to filter out file names that start with 'buy_train_' and end with 0, while also ensuring that any file names that include 2018 are excluded.

The Task Ahead

Let's break down the problem: You want to read files that start with 'buy_train_' and end with 0, but you don’t want to include any files that specifically feature 2018. Here are some examples of file names we need to handle:

Acceptable:

buy_train_2020-01-08_001221_0

buy_train_2020-05-02_067341_0

buy_train_2020-07-26_011901_0

To be filtered out:

buy_train_2018-10-16_617901_0

buy_train_2018-12-19_492111_0

So, how do we accomplish this effectively? Let’s explore both regex and a more straightforward, native Python approach.

Solution Method 1: Using Regular Expressions (Regex)

One prominent way to achieve the filtering task is through regular expressions. Regex allows for sophisticated pattern matching, enabling us to specify exactly which file names to exclude. Here’s how it can be done:

Step-by-Step Process:

Import the Regex Module:
You need to make sure the re module is available in your script.

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

Create Your Regex Filter:
The regex pattern you'll use is 'buy_train_20(?!18)\d*-\d*-\d*_\d*_0'. This pattern works as follows:

buy_train_20 indicates the prefix we want.

(?!18) ensures that any file name containing 2018 directly after buy_train_20 will be excluded.

\d*-\d*-\d*_\d*_0 continues the pattern to match any valid file name structure.

Test the Regex:

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

With this method, you can dynamically filter out files simply by using regex, which is both powerful and flexible.

Solution Method 2: Using Native Python Filtering

If regex feels a bit complicated or overkill for your needs, Python's built-in functionalities can simplify your task. The filter function allows for straightforward filtering based on conditions you define.

Step-by-Step Guide:

Define Your List of File Names:
Start with a list of file paths you want to filter.

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

Create a Filtering Function:
This functional checks if a file starts with buy_train_2018 and filters it out.

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

Apply the Filter:
Use the filter function to apply this to your list of paths.

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

Conclusion

Whether you choose the regex method for its advanced capabilities or the native filter for its simplicity, both options will help you efficiently filter out unwanted files based on naming conventions. Mastering these techniques will improve your Python skills and enhance your ability to manipulate file data effectively.

Feel free to use the example code snippets provided in your own projects, and adapt them as needed to suit your specific file-naming criteria. Happy coding!