How to Replace (Or Strip) an Extension from a Filename in Python

How can I replace (or strip) an extension from a filename in Python?

Try os.path.splitext it should do what you want.

import os
print os.path.splitext('/home/user/somefile.txt')[0]+'.jpg'  # /home/user/somefile.jpg

os.path.splitext('/home/user/somefile.txt')  # returns ('/home/user/somefile', '.txt')

How do I get the filename without the extension from a path in Python?

Getting the name of the file without the extension:

import os
print(os.path.splitext("/path/to/some/file.txt")[0])

Prints:

/path/to/some/file

Documentation for os.path.splitext.

Important Note: If the filename has multiple dots, only the extension after the last one is removed. For example:

import os
print(os.path.splitext("/path/to/some/file.txt.zip.asc")[0])

Prints:

/path/to/some/file.txt.zip

See other answers below if you need to handle that case.

Strip known extension from filename

I would recomment using the OS library.

name, ext = os.path.splitext(path)

Changing file extension in Python

os.path.splitext(), os.rename()

for example:

# renamee is the file getting renamed, pre is the part of file name before extension and ext is current extension
pre, ext = os.path.splitext(renamee)
os.rename(renamee, pre + new_extension)

How can I strip the file extension from a list full of filenames?

You can actually do this in one line with a list comprehension:

lst = [os.path.splitext(x)[0] for x in accounts]

But if you want/need a for-loop, the equivalent code would be:

lst = []
for x in accounts:
    lst.append(os.path.splitext(x)[0])

Notice too that I kept the os.path.splitext(x)[0] part. This is the safest way in Python to remove the extension from a filename. There is no function in the os.path module dedicated to this task and handcrafting a solution with str.split or something would be error prone.

Extracting extension from filename in Python

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', '')

How to change the files extension using python

To begin with , you can store your mappings in a dictionary, then when you are iterating over your folder, and you find the extension, just use the mapping to make the new file name and save it.

import os

folder ="C:/Users/TestFolder"

#Dictionary for extension mappings 
rename_dict = {'txt': 'jpg', 'doc': 'mp3', 'pdf': 'mp4'}
for filename in os.listdir(folder):

    #Get the extension and remove . from it
    base_file, ext = os.path.splitext(filename)
    ext = ext.replace('.','')

    #If you find the extension to rename
    if ext in rename_dict:
        #Create the new file name
        new_ext = rename_dict[ext]
        new_file = base_file + '.' + new_ext

        #Create the full old and new path
        old_path = os.path.join(folder, filename)
        new_path = os.path.join(folder, new_file)

        #Rename the file
        os.rename(old_path, new_path)

How to *not* change the file extension while changing a filename?

You can use pathlib.Path objects. It has name and suffix attributes, and a rename method:

import re
from pathlib import Path
for file in Path(r'C:\tmp').glob('*'):
    if not file.is_file():
        continue
    new_name = re.sub('\d','', file.stem) + file.suffix
    file.rename(file.parent/new_name)

The parent attribute gives the folder the file belongs to and the is_file method is used to check that we are handing a regular file (and not a folder). New Path objects are created easily with the / operator (full new filepath is file.parent / new_name).

The re.sub() is used to replace the numbers (\d means a digit) in the old filename stem part.

remove extension in list python

Remove the extension in a generator expression when you get the filenames with os.path.splitext. Change:

f.extend(filenames)

to:

f.extend(os.path.splitext(name)[0] for name in filenames)

Update: It looks like you're abusing os.walk to do file from directory separation (since you break in the first loop, so you're not actually walking a tree at all), when there are more direct ways to do this. You can replace all of this:

f = [] 
b = os.walk('C:\\Users\\username\\Desktop\\FOLDER')
for(dirpath, dirnames, filenames) in b:
    f.extend(filenames)
    break

on Python 3.5+ (or any version of Python after installing the third party scandir package using scandir.scandir instead of os.scandir), with the more succinct and somewhat faster:

f = [os.path.splitext(e.name)[0] for e in os.scandir(r'C:\Users\username\Desktop\FOLDER')
     if e.is_file()]

which describes what you really want, and by using os.scandir, guarantees you don't have to individually stat each entry in the directory listing to check if it's a file.

If you're on older Python, and can't use the scandir package, at the cost of a stat (which os.walk would pay anyway on older Python), you can do:

f = [os.path.splitext(x)[0] for x in os.listdir(r'C:\Users\username\Desktop\FOLDER')
     if os.path.isfile(os.path.join(r'C:\Users\username\Desktop\FOLDER', x))]

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