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os.walk help

hokiegal99 hokiegal99 at hotmail.com
Mon Nov 24 15:31:02 EST 2003 
This works great! No errors... and it gets dirs that are 8 levels deep 
(that's as far down as I've tested). Thanks for the tip! The re.sub 
seems to be much faster than the string find/replace approach as well... 
I need to read-up more on the documentation of os.walk and re in 
general. Thanks again!!!


Robin Munn wrote:
> Wait, I just realized that you're changing the list *while* you're
> iterating over it. That's a bad idea. See the warning at the bottom of
> this page in the language reference:
> 
>     http://www.python.org/doc/current/ref/for.html
> 
> Instead of modifying the list while you're looping over it, use the
> topdown argument to os.walk to build the tree from the bottom up instead
> of from the top down. That way you won't have to futz with the dirnames
> list at all:
> 
>     def clean_names(rootpath):
>         bad = re.compile(r'%2f|%25|%20|[*?<>/\|\\]')
>         for root, dirs, files in os.walk(rootpath, topdown=False):
>             for dname in dirs:
>                 newdname = re.sub(bad, '-', dname)
>                 if newdname != dname:
>                     newpath = os.path.join(root, newdname)
>                     oldpath = os.path.join(root, dname)
>                     os.renames(oldpath, newpath)
> 
> Notice also the use of re.sub to do all the character substitutions at
> once. Your code as written would have failed on a filename like "foo*?",
> since it always renamed from the original filename: it would have first
> done os.renames("foo*?", "foo-?") followed by os.renames("foo*?",
> "foo--") and the second would have raised an OSError.
>
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