Extracting extension from filename in Python

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Chapters
00:00 Question
00:17 Accepted answer (Score 2529)
00:56 Answer 2 (Score 579)
01:16 Answer 3 (Score 483)
01:26 Answer 4 (Score 141)
01:41 Thank you

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Full question
https://stackoverflow.com/questions/5413...

Accepted answer links:
[os.path.splitext]: https://docs.python.org/3/library/os.pat...

Answer 2 links:
[pathlib]: https://docs.python.org/3/library/pathli...

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https://meta.stackexchange.com/help/lice...

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Tags
#python #filenames #fileextension

#avk47

ACCEPTED ANSWER

Score 2635

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', '')

ANSWER 2

Score 497

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

ANSWER 3

Score 146

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

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

ANSWER 4

Score 113

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