[Tutor] bash find equivalent in Python

[Scott Widney]

> On Fri, 11 Jul 2003, Scott Widney wrote:
> 
> > > def subdirs(root, skip_symlinks = 1):
> > >     """Given a root directory, returns the first-level
> > > subdirectories."""
> > >     try:
> > >         dirs = [os.path.join(root, x)
> > >                 for x in os.listdir(root)]
> > >         dirs = filter(os.path.isdir, dirs)
> >
> > I'm thinking that these two steps can be condensed into one:
> >
> >           dirs = [os.path.join(root, x)
> >                   for x in os.listdir(root)
> >                   if os.path.isdir(x)]
> 
> Hi Scott,
> 
> This almost works.  *grin* We have to do the os.path.join()ing
> thing when we check if it's a directory:
> 
> 
>            dirs = [os.path.join(root, x)
>                    for x in os.listdir(root)
>                    if os.path.isdir(os.path.join(root, x))]
> 
> But this looked a little too ugly, so that's why I broke it 
> down into two steps.
> 
> 
> Is it ok to forward this to Tutor as well?
> 
> 
> Talk to you later!
> 

Ah yes. You're right, why type something twice in such close vicinity? I
don't have an interactive prompt right now to test this:

    dirs = filter(os.path.isdir, [os.path.join(root, x)
                                  for x in os.listdir(root)])

Will Python eval the list comprehension before or during the filter? If it
were to yield the list and filter at the same time, it would fairly fly....