Extracting extension from filename in Python

Question:

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

Asked By: Alex

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Answers:

Use os.path.splitext:

>>> 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', '')
Answered By: nosklo
import os.path
extension = os.path.splitext(filename)[1]
Answered By: Brian Neal
import os.path
extension = os.path.splitext(filename)[1][1:]

To get only the text of the extension, without the dot.

Answered By: wonzbak

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() 
Answered By: yamex5

For simple use cases 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

Also will not work with hidden files in Unix systems:

>>> ".bashrc".split(".")[-1]
'bashrc'    # But this is not an extension

For general use, prefer os.path.splitext

Answered By: Murat Çorlu

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()
Answered By: blented

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

Answered By: XavierCLL

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])
filename='ext.tar.gz'
extension = filename[filename.rfind('.'):]
Answered By: staytime
name_only=file_name[:filename.index(".")

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

Answered By: wookie
# 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 ""
Answered By: DragonX
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
Answered By: user5535053

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
Answered By: PascalVKooten

New in version 3.4.

import pathlib

print(pathlib.Path('yourPath.example').suffix) # '.example'
print(pathlib.Path("hello/foo.bar.tar.gz").suffixes) # ['.bar', '.tar', '.gz']

I’m surprised no one has mentioned pathlib yet, pathlib IS awesome!

Answered By: jeromej

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’

Answered By: weiyixie

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'
Answered By: Execuday

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

Answered By: soheshdoshi

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]
Answered By: Kenstars

You can find some great stuff in pathlib module (available in python 3.x).

import pathlib
x = pathlib.PurePosixPath("C:\Path\To\File\myfile.txt").suffix
print(x)

# Output 
'.txt'
Answered By: r3t40

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'
Answered By: Alex

This is The Simplest Method to get both Filename & Extension in just a single line.

fName, ext = 'C:/folder name/Flower.jpeg'.split('/')[-1].split('.')

>>> print(fName)
Flower
>>> print(ext)
jpeg

Unlike other solutions, you don’t need to import any package for this.

Answered By: Ripon Kumar Saha

For funsies… just collect the extensions in a dict, and track all of them in a folder. Then just pull the extensions you want.

import os

search = {}

for f in os.listdir(os.getcwd()):
    fn, fe = os.path.splitext(f)
    try:
        search[fe].append(f)
    except:
        search[fe]=[f,]

extensions = ('.png','.jpg')
for ex in extensions:
    found = search.get(ex,'')
    if found:
        print(found)
Answered By: eatmeimadanish

A true one-liner, if you like regex.
And it doesn’t matter even if you have additional “.” in the middle

import re

file_ext = re.search(r".([^.]+)$", filename).group(1)

See here for the result: Click Here

Answered By: Victor Wang

try this:

files = ['file.jpeg','file.tar.gz','file.png','file.foo.bar','file.etc']
pen_ext = ['foo', 'tar', 'bar', 'etc']

for file in files: #1
    if (file.split(".")[-2] in pen_ext): #2
        ext =  file.split(".")[-2]+"."+file.split(".")[-1]#3
    else:
        ext = file.split(".")[-1] #4
    print (ext) #5
  1. get all file name inside the list
  2. splitting file name and check the penultimate extension, is it in the pen_ext list or not?
  3. if yes then join it with the last extension and set it as the file’s extension
  4. if not then just put the last extension as the file’s extension
  5. and then check it out
Answered By: Ibnul Husainan
a = ".bashrc"
b = "text.txt"
extension_a = a.split(".")
extension_b = b.split(".")
print(extension_a[-1])  # bashrc
print(extension_b[-1])  # txt
Answered By: lendoo

you can use following code to split file name and extension.

    import os.path
    filenamewithext = os.path.basename(filepath)
    filename, ext = os.path.splitext(filenamewithext)
    #print file name
    print(filename)
    #print file extension
    print(ext)
Answered By: Muhammad Salman

Extracting extension from filename in Python

Python os module splitext()

splitext() function splits the file path into a tuple having two values – root and extension.

import os
# unpacking the tuple
file_name, file_extension = os.path.splitext("/Users/Username/abc.txt")
print(file_name)
print(file_extension)

Get File Extension using Pathlib Module

Pathlib module to get the file extension

import pathlib
pathlib.Path("/Users/pankaj/abc.txt").suffix
#output:'.txt'
Answered By: DS_ShraShetty

You can use endswith to identify the file extension in python

like bellow example

for file in os.listdir():
    if file.endswith('.csv'):
        df1 =pd.read_csv(file)
        frames.append(df1)
        result = pd.concat(frames)
Answered By: cng.buff

This method will require a dictonary, list, or set. you can just use ".endswith" using built in string methods. This will search for name in list at end of file and can be done with just str.endswith(fileName[index]). This is more for getting and comparing extensions.

https://docs.python.org/3/library/stdtypes.html#string-methods

Example 1:

dictonary = {0:".tar.gz", 1:".txt", 2:".exe", 3:".js", 4:".java", 5:".python", 6:".ruby",7:".c", 8:".bash", 9:".ps1", 10:".html", 11:".html5", 12:".css", 13:".json", 14:".abc"} 
for x in dictonary.values():
    str = "file" + x
    str.endswith(x, str.index("."), len(str))

Example 2:

set1 = {".tar.gz", ".txt", ".exe", ".js", ".java", ".python", ".ruby", ".c", ".bash", ".ps1", ".html", ".html5", ".css", ".json", ".abc"}
for x in set1:
   str = "file" + x
   str.endswith(x, str.index("."), len(str))

Example 3:

fileName = [".tar.gz", ".txt", ".exe", ".js", ".java", ".python", ".ruby", ".c", ".bash", ".ps1", ".html", ".html5", ".css", ".json", ".abc"];
for x in range(0, len(fileName)):
    str = "file" + fileName[x]
    str.endswith(fileName[x], str.index("."), len(str))

Example 4

fileName = [".tar.gz", ".txt", ".exe", ".js", ".java", ".python", ".ruby", ".c", ".bash", ".ps1", ".html", ".html5", ".css", ".json", ".abc"];
str = "file.txt"
str.endswith(fileName[1], str.index("."), len(str))

Examples 5, 6, 7 with output
enter image description here

Example 8

fileName = [".tar.gz", ".txt", ".exe", ".js", ".java", ".python", ".ruby", ".c", ".bash", ".ps1", ".html", ".html5", ".css", ".json", ".abc"];
exts = []
str = "file.txt"
for x in range(0, len(x)):
    if str.endswith(fileName[1]) == 1:
         exts += [x]
     
Answered By: Import Error
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