Python And File Paths

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))