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

Question

Hi,

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

Sorry if my question is really trivial, but I'm learning Python for 2 hours now and I didn't found a way to do this in the official docs or even on Google.

Thanks.

P.S: 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 ?)

P.S2: 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)

Answer 1

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

Answer 2

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.