Extracting extension from filename in Python
-
23-08-2019 - |
Question
Is there a function to extract the extension from a filename?
Solution
Yes. Use os.path.splitext
(see Python 2.X documentation or Python 3.X documentation):
>>> import os
>>> filename, file_extension = os.path.splitext('/path/to/somefile.ext')
>>> filename
'/path/to/somefile'
>>> file_extension
'.ext'
Unlike most manual string-splitting attempts, os.path.splitext
will correctly treat /a/b.c/d
as having no extension instead of having extension .c/d
, and it will treat .bashrc
as having no extension instead of having extension .bashrc
:
>>> os.path.splitext('/a/b.c/d')
('/a/b.c/d', '')
>>> os.path.splitext('.bashrc')
('.bashrc', '')
OTHER TIPS
import os.path
extension = os.path.splitext(filename)[1]
New in version 3.4.
import pathlib
print(pathlib.Path('yourPathGoesHere').suffix)
I'm surprised no one has mentioned pathlib
yet, pathlib
IS awesome!
If you need all the suffixes (eg if you have a .tar.gz
), .suffixes
will return a list of them!
import os.path
extension = os.path.splitext(filename)[1][1:]
To get only the text of the extension, without the dot.
One option may be splitting from dot:
>>> filename = "example.jpeg"
>>> filename.split(".")[-1]
'jpeg'
No error when file doesn't have an extension:
>>> "filename".split(".")[-1]
'filename'
But you must be careful:
>>> "png".split(".")[-1]
'png' # But file doesn't have an extension
worth adding a lower in there so you don't find yourself wondering why the JPG's aren't showing up in your list.
os.path.splitext(filename)[1][1:].strip().lower()
Any of the solutions above work, but on linux I have found that there is a newline at the end of the extension string which will prevent matches from succeeding. Add the strip()
method to the end. For example:
import os.path
extension = os.path.splitext(filename)[1][1:].strip()
With splitext there are problems with files with double extension (e.g. file.tar.gz
, file.tar.bz2
, etc..)
>>> fileName, fileExtension = os.path.splitext('/path/to/somefile.tar.gz')
>>> fileExtension
'.gz'
but should be: .tar.gz
The possible solutions are here
Although it is an old topic, but i wonder why there is none mentioning a very simple api of python called rpartition in this case:
to get extension of a given file absolute path, you can simply type:
filepath.rpartition('.')[-1]
example:
path = '/home/jersey/remote/data/test.csv'
print path.rpartition('.')[-1]
will give you: 'csv'
filename='ext.tar.gz'
extension = filename[filename.rfind('.'):]
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
You can find some great stuff in pathlib module.
import pathlib
x = pathlib.PurePosixPath("C:\\Path\\To\\File\\myfile.txt").suffix
print(x)
# Output
'.txt'
You can use a split
on a filename
:
f_extns = filename.split(".")
print ("The extension of the file is : " + repr(f_extns[-1]))
This does not require additional library
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'
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]
Another solution with right split:
# to get extension only
s = 'test.ext'
if '.' in s: ext = s.rsplit('.', 1)[1]
# or, to get file name and extension
def split_filepath(s):
"""
get filename and extension from filepath
filepath -> (filename, extension)
"""
if not '.' in s: return (s, '')
r = s.rsplit('.', 1)
return (r[0], r[1])
Even this question is already answered I'd add the solution in Regex.
>>> import re
>>> file_suffix = ".*(\..*)"
>>> result = re.search(file_suffix, "somefile.ext")
>>> result.group(1)
'.ext'
def NewFileName(fichier):
cpt = 0
fic , *ext = fichier.split('.')
ext = '.'.join(ext)
while os.path.isfile(fichier):
cpt += 1
fichier = '{0}-({1}).{2}'.format(fic, cpt, ext)
return fichier
# 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 ""
name_only=file_name[:filename.index(".")
That will give you the file name up to the first ".", which would be the most common.