How to Filter File Names by Number Range in Python Using Regex

This guide explains how to efficiently filter file names containing numeric values within a specified range using Python's regex capabilities.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: For a given range of (x,y) how do I return the list of files with numbers within x, y in their name

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Filter File Names by Number Range in Python Using Regex

Have you ever found yourself needing to sift through a long list of files, only to find that the files you want are buried under a mountain of others? If you're working with file names that contain numbers, this can be particularly cumbersome. In this post, we'll address a common issue: how to return a list of files that have numbers within a specified range in their names.

The Problem

For instance, let’s say you have a folder filled with files named something like posture0, posture1, posture2, all the way up to posture4000. Suppose you're interested in collecting the files that fall within different numerical ranges, such as (1-300) or (2-219). As it turns out, automating this task effectively can be more complex than it seems.

Why Regex Can Be Tricky

Initially, you might try using regex (regular expressions) to match files, expecting it to all just work out of the box. However, regex can sometimes yield unexpected matches or miss certain files entirely. For example, you may find that your regex correctly matches files from 0-180, yet it might overlook files from 0-99 while improperly matching posture1000—a clear example of how regex can prove challenging without precise crafting.

The Elegant Solution

So, how can we efficiently extract the file names based on a given numerical range using Python? Below, I will provide a function using the os and re modules that does exactly this.

Step-by-Step Breakdown of the Solution

1. Setting Up the Environment

You need to ensure that you have Python installed, along with the necessary libraries. The os library will help us interact with the operating system to list files. The re library will handle our regex needs.

2. Creating the Function

Here’s a Python function that, when provided with a directory path, a lower limit, and an upper limit, will return a list of file names containing numbers within that range.

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

3. Understanding the Code: Key Components

Range Check: The number extracted from the file name is checked against the specified range, and if it falls within that range, it is added to the results.

4. Using the Function

To employ this function, you would call it and provide the directory along with the numeric bounds desired. For example:

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

Conclusion

With this function, you can easily filter through your files based on the numeric portions of their names. While regex can be a tricky tool, breaking down the problem and leveraging powerful libraries like os and re makes it manageable.

Feel free to adjust the function to suit your specific filenames or requirements, and happy coding!