PYTHON

Python And File Paths

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Overview

The pathlib Module

The pathlib module was introduced in Python v3.4 (PEP 428). It’s purpose was to replace the much used functions such as os.path.join() and family with a simpler set of path manipulating classes/functions which work similarly across all platforms. In the words of PEP 428, it is “object-orientated file-system paths”.

On Linux/macOS:

file_path = Path('~/my_file.txt')

On Windows you would also use forward slashes to describe paths! The Path module recognizes you are running the code on Windows and converts the path accordingly.

file_path = Path('C:/Users/my_file.txt')

os.path.join() has long been the mainstay of concatenating paths in cross-platform way. For instance, os.path.join('my_dir', 'my_file') would result in the string my_dir/my_file in Linux-like (POSIX) systems, and my_dir\my_file on Windows systems. The pathlib module aims to make os.path.join() redundant by overloading the / (slash) operator to allow the concatenation of path segments:

file_path = Path('my_dir') / 'my_file'

Once you have a Path object, you can check if something exists at that path (typically it would point to a directory or file) by calling .exists():

my_path = Path('my_file.txt')
my_path.exists()
# Returns True if text file exists

Getting Parts Of The Path

The Path object provides many properties to extract different parts of a path:

my_path = Path('/my_dir/my_file.txt')

print(my_path.parent) # '/my_dir'
print(my_path.name) # 'my_file.txt'
print(my_path.stem) # 'my_file'
print(my_path.suffix) # '.txt'
print(my_path.root) # '/'
print(my_path.parts) # ('/', 'my_dir', 'my_file.txt')

Note that in Linux systems, .root is typically /, while in Windows system, .root is typically \\.

.stem allows you to extract the filename without the extension, which replaces os.path.splitext()[0]

Backwards Compatibility

If you start using Path objects in your code but have to interacts with pre-existing code which uses plain strings for paths, you will have to convert the Path object to a string first, which is easily done with the str() cast:

my_path = Path('my_file.txt')
old_function(str(my_path))

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