newb question: file searching

[hiaips]

jaysherby at gmail.com wrote:
> Thanks, Dave.  That's exactly what I was looking for, well, except for
> a few small alterations I'll make to achieve the desired effect.  I
> must ask, in the interest of learning, what is
>
> [file for file in files if file.endswith(extension)]
>
> actually doing?  I know that 'file' is a type, but what's with the set
> up and the brackets and all?  Can someone run down the syntax for me on
> that?  And also, I'm still not sure I know exactly how os.walk() works.
>  And, finally, the python docs all note that symbols like . and ..
> don't work with these commands.  How can I grab the directory that my
> script is residing in?

[file for file in files if file.endswith(extension)] is called a list
comprehension. Functionally, it is equivalent to something like this:
files_with_ext = []
for file in files:
  if file.endswith(extension):
    files_with_ext.append(file)
However, list comprehensions provide a much more terse, declarative
syntax without sacrificing readability.

To get your current working directory (i.e., the directory in which
your script is residing):
cwd = os.getcwd()

As far as os.walk...
This is actually a generator (effectively, a function that eventually
produces a sequence, but rather than returning the entire sequence, it
"yields" one value at a time). You might use it as follows:
for x in os.walk(mydirectory):
  for file in x[1]:
     <whatever tests or code you need to run>

You might want to read up on the os and os.path modules - these
probably have many of the utilities you're looking for.

Good luck,
dave