Get the filename, directory, extension from a path string in Python | note.nkmk.me (2024)

In Python, you can get the filename (basename), directory (folder) name, and extension from a path string or join the strings to generate the path string with the os.path module in the standard library.

• os.path — Common pathname manipulations — Python 3.11.3 documentation

Use the following path string as an example.

import osfilepath = './dir/subdir/filename.ext'

The sample code below is running on a Mac. Examples for Windows are shown at the end.

This article explains how to obtain file and directory names from path strings. Refer to the following article if you want to obtain a list of file and directory names in a directory.

• Get a list of file and directory names in Python

In Python 3.4 or later, you can also get the filename, directory (folder) name, extension, etc., with the pathlib module that treats paths as objects.

• pathlib — Object-oriented filesystem paths — Python 3.9.1rc1 documentation

Difference in path separator by OS

The path separator varies depending on the OS. UNIX (including Mac) uses the slash /, while Windows uses the backslash \.

You can get the separator in the OS running Python with os.sep or os.path.sep.

print(os.sep)# /print(os.sep is os.path.sep)# True

Get the filename (basename) from a path: os.path.basename()

Use os.path.basename() to get the filename (basename) from a path string.

Filename with extension

os.path.basename() returns the filename with the extension.

filepath = './dir/subdir/filename.ext'basename = os.path.basename(filepath)print(basename)# filename.extprint(type(basename))# <class 'str'>

Filename without extension

You can get the filename without the extension with os.path.splitext() described later.

filepath = './dir/subdir/filename.ext'basename_without_ext = os.path.splitext(os.path.basename(filepath))[0]print(basename_without_ext)# filename

os.path.splitext() split at the last (right) dot .. If you want to split by the first (left) dot ., use split().

• Split a string in Python (delimiter, line break, regex, and more)

filepath_tar_gz = './dir/subdir/filename.tar.gz'print(os.path.splitext(os.path.basename(filepath_tar_gz))[0])# filename.tarprint(os.path.basename(filepath_tar_gz).split('.', 1)[0])# filename

Get the directory (folder) name from a path: os.path.dirname()

Use os.path.dirname() to get the directory folder (name) from a path string.

filepath = './dir/subdir/filename.ext'dirname = os.path.dirname(filepath)print(dirname)# ./dir/subdirprint(type(dirname))# <class 'str'>

If you want to get only the directory name directly above the file, use os.path.basename().

subdirname = os.path.basename(os.path.dirname(filepath))print(subdirname)# subdir

Get the file and directory name pair: os.path.split()

Use os.path.split() to get both the file and directory (folder) name.

os.path.split() returns a tuple of filename returned by os.path.basename() and directory name returned by os.path.dirname().

filepath = './dir/subdir/filename.ext'base_dir_pair = os.path.split(filepath)print(base_dir_pair)# ('./dir/subdir', 'filename.ext')print(type(base_dir_pair))# <class 'tuple'>print(os.path.split(filepath)[0] == os.path.dirname(filepath))# Trueprint(os.path.split(filepath)[1] == os.path.basename(filepath))# True

You can unpack tuple to assign to each variable.

• Unpack a tuple and list in Python

dirname, basename = os.path.split(filepath)print(dirname)# ./dir/subdirprint(basename)# filename.ext

Use os.path.join() described later to rejoin the file and directory names.

Notes on when a path string indicates a directory

Note that the result will differ for a path string indicating a directory (folder) based on the presence or absence of a separator at the end.

No separator at the end:

dirpath_without_sep = './dir/subdir'print(os.path.split(dirpath_without_sep))# ('./dir', 'subdir')print(os.path.basename(dirpath_without_sep))# subdir

If there is a separator at the end, use os.path.dirname() and os.path.basename() to get the bottom folder name.

dirpath_with_sep = './dir/subdir/'print(os.path.split(dirpath_with_sep))# ('./dir/subdir', '')print(os.path.basename(os.path.dirname(dirpath_with_sep)))# subdir

Get the extension: os.path.splitext()

Use os.path.splitext() to get the extension.

os.path.splitext() splits the extension and others and returns it as a tuple. The extension contains the dot ..

filepath = './dir/subdir/filename.ext'root_ext_pair = os.path.splitext(filepath)print(root_ext_pair)# ('./dir/subdir/filename', '.ext')print(type(root_ext_pair))# <class 'tuple'>

You can concatenate with the + operator to return the original path string.

• Concatenate strings in Python (+ operator, join, etc.)

root, ext = os.path.splitext(filepath)print(root)# ./dir/subdir/filenameprint(ext)# .extpath = root + extprint(path)# ./dir/subdir/filename.ext

Create a path string with a different extension

To create a path string with only the extension changed from the original, concatenate the first element of the tuple returned by os.path.splitext() with any extension.

filepath = './dir/subdir/filename.ext'other_ext_filepath = os.path.splitext(filepath)[0] + '.jpg'print(other_ext_filepath)# ./dir/subdir/filename.jpg

Get the extension without dot (period)

If you want to get the extension without the dot (period) ., specify the second and subsequent strings with slice [1:].

• How to slice a list, string, tuple in Python

filepath = './dir/subdir/filename.ext'ext_without_dot = os.path.splitext(filepath)[1][1:]print(ext_without_dot)# ext

Examples of cases like .tar.gz

Note that os.path.splitext() splits at the last (right) dot . as demonstrated in the previous example. Be cautious with extensions like .tar.gz.

filepath_tar_gz = './dir/subdir/filename.tar.gz'print(os.path.splitext(filepath_tar_gz))# ('./dir/subdir/filename.tar', '.gz')

If you want to split by the first (left) dot . in the file name, use the split() method of the string, but it doesn't work if the directory name also contains the dot..

print(filepath_tar_gz.split('.', 1))# ['', '/dir/subdir/filename.tar.gz']

After splitting with os.path.split(), apply the split() method of the string and join with os.path.join() described later.

The string returned by split() does not contain a delimiter, so be careful if you want to get an extension with a dot . like os.path.splitext().

dirname, basename = os.path.split(filepath_tar_gz)basename_without_ext, ext = basename.split('.', 1)path_without_ext = os.path.join(dirname, basename_without_ext)print(path_without_ext)# ./dir/subdir/filenameprint(ext)# tar.gzext_with_dot = '.' + extprint(ext_with_dot)# .tar.gz

Create a path string by combining the file and directory names: os.path.join()

Use os.path.join() to join file and directory names to create a new path string.

path = os.path.join('dir', 'subdir', 'filename.ext')print(path)# dir/subdir/filename.ext

Create a path string for another file in the same directory

If you want to create a path string for another file in the same directory of one file, use os.path.dirname() and os.path.join().

filepath = './dir/subdir/filename.ext'other_filepath = os.path.join(os.path.dirname(filepath), 'other_file.ext')print(other_filepath)# ./dir/subdir/other_file.ext

Use different OS formats

If you want to manipulate path strings in an OS format that is not the OS on which Python is currently running, import and use different modules instead of the os module.

• UNIX (including current Mac): posixpath
• Windows: ntpath
• Macintosh 9 and earlier: macpath

Since each module has the same interface as os.path, you can change the os.path part of the sample code so far to their module names (such as ntpath).

Examples for Windows

The sample code below is running on Mac using the ntpath module mentioned above. When running on Windows, you can replace ntpath with os.path.

Backslash and raw string

The path separator in Windows is the backslash \.

To write a backslash in a string, you need to write two backslashes to escape. print() outputs one backslash.

• 2. Lexical analysis - String and Bytes literals — Python 3.9.1rc1 documentation

import ntpathprint(ntpath.sep)# \print('\\')# \print(ntpath.sep is '\\')# True

Using a raw string (r'xxx') simplifies writing a Windows path, as it allows you to write a backslash directly. Raw strings and normal strings have equal value.

file_path = 'c:\\dir\\subdir\\filename.ext'file_path_raw = r'c:\dir\subdir\filename.ext'print(file_path == file_path_raw)# True

For more information about raw strings, see the following article.

• Raw strings in Python

Examples of getting file name, folder name, extension

These examples also work on Windows.

print(ntpath.basename(file_path))# filename.extprint(ntpath.dirname(file_path))# c:\dir\subdirprint(ntpath.split(file_path))# ('c:\\dir\\subdir', 'filename.ext')

Get and join a drive letter: os.path.splitdrive()

Use os.path.splitdrive() to get the drive letter. The sample code below uses ntpath.splitdrive().

os.path.splitdrive() splits the drive letter including the colon : and others.

print(ntpath.splitdrive(file_path))# ('c:', '\\dir\\subdir\\filename.ext')

If you want to get only the drive letter, select the first character.

drive_letter = ntpath.splitdrive(file_path)[0][0]print(drive_letter)# c

Be careful when joining drive characters.

If you pass it to os.path.join() as it is, it will not work.

print(ntpath.join('c:', 'dir', 'subdir', 'filename.ext'))# c:dir\subdir\filename.ext

You can also specify os.sep (ntpath.sep in the sample code) for the argument of os.path.join() or add a separator to the drive letter.

print(ntpath.join('c:', ntpath.sep, 'dir', 'subdir', 'filename.ext'))# c:\dir\subdir\filename.extprint(ntpath.join('c:\\', 'dir', 'subdir', 'filename.ext'))# c:\dir\subdir\filename.ext