Is there a built-in function in Python that would replace (or remove, whatever) the extension of a filename (if it has one)?
Example:
print replace_extension('/home/user/somefile.txt', '.jpg')
In my example: /home/user/somefile.txt
would become /home/user/somefile.jpg
I don't know if it matters, but I need this for a SCons module I'm writing. (So perhaps there is some SCons specific function I can use ?)
I'd like something clean. Doing a simple string replacement of all occurrences of .txt
within the string is obviously not clean. (This would fail if my filename is somefile.txt.txt.txt
)
Expanding on AnaPana's answer, how to remove an extension using pathlib (Python >= 3.4):
>>> from pathlib import Path
>>> filename = Path('/some/path/somefile.txt')
>>> filename_wo_ext = filename.with_suffix('')
>>> filename_replace_ext = filename.with_suffix('.jpg')
>>> print(filename)
/some/path/somefile.ext
>>> print(filename_wo_ext)
/some/path/somefile
>>> print(filename_replace_ext)
/some/path/somefile.jpg
I prefer the following one-liner approach using str.rsplit():
my_filename.rsplit('.', 1)[0] + '.jpg'
Example:
>>> my_filename = '/home/user/somefile.txt'
>>> my_filename.rsplit('.', 1)
>>> ['/home/user/somefile', 'txt']
I'm surprised nobody has mentioned pathlib's with_name
. This solution works with multiple extensions (i.e. it replaces all of the extensions.)
import pathlib
p = pathlib.Path('/some/path/somefile.txt')
p = p.with_name(p.stem).with_suffix('.jpg')
Another way to do is to use the str.rpartition(sep)
method.
For example:
filename = '/home/user/somefile.txt'
(prefix, sep, suffix) = filename.rpartition('.')
new_filename = prefix + '.jpg'
print new_filename
As @jethro said, splitext
is the neat way to do it. But in this case, it's pretty easy to split it yourself, since the extension must be the part of the filename coming after the final period:
filename = '/home/user/somefile.txt'
print( filename.rsplit( ".", 1 )[ 0 ] )
# '/home/user/somefile'
The rsplit
tells Python to perform the string splits starting from the right of the string, and the 1
says to perform at most one split (so that e.g. 'foo.bar.baz'
-> [ 'foo.bar', 'baz' ]
). Since rsplit
will always return a non-empty array, we may safely index 0
into it to get the filename minus the extension.
For Python >= 3.4:
from pathlib import Path
filename = '/home/user/somefile.txt'
p = Path(filename)
new_filename = p.parent.joinpath(p.stem + '.jpg') # PosixPath('/home/user/somefile.jpg')
new_filename_str = str(new_filename) # '/home/user/somefile.jpg'
In the case where you have multiple extensions this one-liner using pathlib
and str.replace
works a treat:
>>> from pathlib import Path
>>> p = Path("/path/to/myfile.tar.gz")
>>> extensions = "".join(p.suffixes)
# any python version
>>> str(p).replace(extensions, "")
'/path/to/myfile'
# python>=3.9
>>> str(p).removesuffix(extensions)
'/path/to/myfile'
>>> p = Path("/path/to/myfile.tar.gz")
>>> extensions = "".join(p.suffixes)
>>> new_ext = ".jpg"
>>> str(p).replace(extensions, new_ext)
'/path/to/myfile.jpg'
If you also want a pathlib
object output then you can obviously wrap the line in Path()
>>> Path(str(p).replace("".join(p.suffixes), ""))
PosixPath('/path/to/myfile')
from pathlib import Path
from typing import Union
PathLike = Union[str, Path]
def replace_ext(path: PathLike, new_ext: str = "") -> Path:
extensions = "".join(Path(path).suffixes)
return Path(str(p).replace(extensions, new_ext))
p = Path("/path/to/myfile.tar.gz")
new_ext = ".jpg"
assert replace_ext(p, new_ext) == Path('/path/to/myfile.jpg')
assert replace_ext(str(p), new_ext) == Path('/path/to/myfile.jpg')
assert replace_ext(p) == Path('/path/to/myfile')
Source: Stackoverflow.com