Explained: How to Effortlessly List Files in Directory

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How to Get a List of All Files in a Directory With Python

When working with file-related operations in Python, one common task is to get a list of all the files and folders in a directory. This step is often the starting point for many file operations. In Python, there are multiple ways to accomplish this task, each with its own advantages and trade-offs.

In this tutorial, we will explore the most general-purpose techniques using the pathlib module for listing items in a directory. Additionally, we will also briefly discuss some alternative tools.

Getting Started with pathlib

Before the introduction of the pathlib module in Python 3.4, the standard way to work with file paths was to use the os module. While this approach was efficient in terms of performance, it required handling paths as strings.

However, manipulating paths as strings can become cumbersome, especially when dealing with multiple operating systems. Additionally, the code can quickly become abstracted from the actual file path, making it difficult to understand.

To address this, the pathlib module was introduced, which provides an object-oriented approach to working with file paths. It simplifies many of the complexities involved and allows developers to focus on the main logic of their code.

To begin using pathlib, you need to create a Path object. The type of Path object depends on the operating system. On Windows, you will work with a WindowsPath object, while on Linux and macOS, you will use a PosixPath object.

Here’s an example of creating a Path object for a directory:

import pathlib

# Windows
desktop = pathlib.Path("C:/Users/RealPython/Desktop")
print(desktop)  # Output: WindowsPath("C:/Users/RealPython/Desktop")

# Linux + macOS
desktop = pathlib.Path("/home/RealPython/Desktop")
print(desktop)  # Output: PosixPath('/home/RealPython/Desktop')

With the Path object, you can utilize its methods and properties to perform various operations on directories and files.

Getting a List of All Files and Folders in a Directory

Now that we have a basic understanding of pathlib, let’s dive into the process of getting a list of all files and folders in a directory.

To accomplish this, we can use the iterdir() method, which returns an iterator of the items in the directory. We can then loop through this iterator to access each item.

Here’s an example that demonstrates this process:

import pathlib

directory = pathlib.Path("/path/to/directory") # Replace with the actual directory path

for item in directory.iterdir():
    print(item)

By running this code, you will see a list of all the items (both files and folders) present in the specified directory.

Recursively Listing With .rglob()

In some cases, you may need to recursively list all files and folders within a directory, including those in subdirectories. pathlib provides the .rglob() method, which allows you to perform recursive listing.

Here’s an example:

import pathlib

directory = pathlib.Path("/path/to/directory") # Replace with the actual directory path

for item in directory.rglob("*"):
    print(item)

This code will traverse through all subdirectories, listing every item it encounters.

Using a Python Glob Pattern for Conditional Listing

If you want to list only specific files or folders based on specific conditions, you can use glob patterns. A glob pattern is a string that contains special characters to match filenames or paths.

Conditional Listing Using .glob()

The .glob() method allows you to list items in a directory based on a glob pattern. It returns an iterator that yields the matching items.

Here’s an example:

import pathlib

directory = pathlib.Path("/path/to/directory") # Replace with the actual directory path

for item in directory.glob("*.txt"):
    print(item)

This code lists all the files in the directory with a .txt extension.

Conditional Listing Using .rglob()

Similar to .glob(), .rglob() also supports glob patterns for recursive listing. You can use it to filter items based on specific conditions.

Here’s an example:

import pathlib

directory = pathlib.Path("/path/to/directory") # Replace with the actual directory path

for item in directory.rglob("*.txt"):
    print(item)

This code recursively lists all the files with a .txt extension in the directory and its subdirectories.

Advanced Matching With the Glob Methods

The glob patterns used in the examples above are simple, but you can also use more advanced patterns by leveraging the power of regular expressions. This provides greater flexibility when filtering items based on complex conditions.

import pathlib
import re

directory = pathlib.Path("/path/to/directory") # Replace with the actual directory path

pattern = re.compile(r"file_\d{3}.txt")  # Matches files with names like file_001.txt, file_002.txt, etc.

for item in directory.glob("*"):
    if pattern.match(item.name):
        print(item)

This code uses a regular expression pattern to match files with names like file_001.txt, file_002.txt, and so on.

Opting Out of Listing Junk Directories

When listing items in a directory, you may come across directories that you want to exclude from the list. One approach is to use the .rglob() method to filter out entire directories based on specific conditions.

Here’s an example:

import pathlib

directory = pathlib.Path("/path/to/directory") # Replace with the actual directory path

for item in directory.rglob("*"):
    if not item.is_dir():
        print(item)

By checking if an item is a directory (item.is_dir()), you can exclude directories from being listed.

Conclusion

In this tutorial, we explored different techniques for getting a list of all files and folders in a directory using the pathlib module in Python. We learned how to list items in a directory, perform recursive listing, and filter items based on specific conditions using glob patterns.

The pathlib module provides a clean and intuitive way to work with file paths, simplifying many of the complexities involved. By leveraging its methods and properties, you can easily manipulate file paths and perform various file-related operations.

Now it’s time to apply these techniques in your own projects and enhance your file-processing capabilities with Python!