How to change the file extension in files in a list

Question

I have this code for opening a folder with these directories. Some of them have the extension html but not all of them. How can I change all the files in my three subdirectories that do not have an extension html in .html ?

from os import walk
mypath = ("/directory/path/to/folder")
f = []
for (dirpath,dirnames,filenames) in walk(mypath):
    f.extend(filenames)
    print(f)

Answer 1

If you are on Python 3.4 or higher, consider using pathlib.

Here is a solution for your problem using that:

from pathlib import Path

mypath = Path('/directory/path/to/folder')

for f in mypath.iterdir():
    if f.is_file() and not f.suffix:
        f.rename(f.with_suffix('.html'))

If you need to walk down to sub-directories as well, you can use the Path.glob() method to list all directories recursively and then process each file in that directory. Something like this:

from pathlib import Path

mypath = Path('/directory/path/to/folder')

for dir in mypath.glob('**'):
    for f in dir.iterdir():
        if f.is_file() and not f.suffix:
            f.rename(f.with_suffix('.html'))

And here is one more way to walk down all directories and process all files:

from pathlib import Path

mypath = Path('/directory/path/to/folder')

for f in mypath.glob('*'):
    if f.is_file() and not f.suffix:
        f.rename(f.with_suffix('.html'))

Using Path.glob() with two asterisks will list all sub-directories and with just one asterisk it will list everything down that path.

I hope that helps.