[Tutor] Re: glob or filter help

[Jeff Shannon]

Barnaby Scott wrote:

> For anyone who doesn't like lambda, how about
> 
> import os
> def get_fles(exts, upd_dir):
> 	return [i for i in os.listdir(upd_dir) if i.split('.')[-1] in exts]

Better would be:

def get_fles(exts, upd_dir):
     return [fname for fname in os.listdir(upd_dir) if \
                os.path.splitext(fname)[-1] in exts \
                and not fname.islink() ]

(This is split into three lines for readability, but can be entered as 
a single line.  Also, the '\' line-continuation is optional, as Python 
will see that the list comp is still open and automatically continue 
the line...)

Using os.path.splitext() to get the extension is safer and more 
portable than simply splitting on '.', and it's self-documenting too! 
  (A month from now, you might need to think a moment to figure out 
why you're splitting on '.', but the very name os.path.splitext() 
tells you about the intent.)

Note that there's a slight difference here, in that exts will need to 
list extensions *with* the leading '.' because splitext() will leave 
it on --

 >>> os.path.splitext('filename.txt')
('filename', '.txt')
 >>>

I've also added a second clause to ensure that returned files are not 
links, as per the rest of the O.P.'s spec.

Jeff Shannon
Technician/Programmer
Credit International