Extracting extension from filename in Python

Question

Is there a function to extract the extension from a filename?

Answer 1

import os.path
extension = os.path.splitext(filename)[1]

Answer 2

Just join all pathlib suffixes.

>>> x = 'file/path/archive.tar.gz'
>>> y = 'file/path/text.txt'
>>> ''.join(pathlib.Path(x).suffixes)
'.tar.gz'
>>> ''.join(pathlib.Path(y).suffixes)
'.txt'

Answer 3

Surprised this wasn't mentioned yet:

import os
fn = '/some/path/a.tar.gz'

basename = os.path.basename(fn)  # os independent
Out[] a.tar.gz

base = basename.split('.')[0]
Out[] a

ext = '.'.join(basename.split('.')[1:])   # <-- main part

# if you want a leading '.', and if no result `None`:
ext = '.' + ext if ext else None
Out[] .tar.gz

Benefits:

• Works as expected for anything I can think of
• No modules
• No regex
• Cross-platform
• Easily extendible (e.g. no leading dots for extension, only last part of extension)

As function:

def get_extension(filename):
    basename = os.path.basename(filename)  # os independent
    ext = '.'.join(basename.split('.')[1:])
    return '.' + ext if ext else None

Answer 4

# try this, it works for anything, any length of extension
# e.g www.google.com/downloads/file1.gz.rs -> .gz.rs

import os.path

class LinkChecker:

    @staticmethod
    def get_link_extension(link: str)->str:
        if link is None or link == "":
            return ""
        else:
            paths = os.path.splitext(link)
            ext = paths[1]
            new_link = paths[0]
            if ext != "":
                return LinkChecker.get_link_extension(new_link) + ext
            else:
                return ""

Answer 5

This is a direct string representation techniques : I see a lot of solutions mentioned, but I think most are looking at split. Split however does it at every occurrence of "." . What you would rather be looking for is partition.

string = "folder/to_path/filename.ext"
extension = string.rpartition(".")[-1]

Answer 6

name_only=file_name[:filename.index(".")

That will give you the file name up to the first ".", which would be the most common.