[Tutor] Reading and Writing

[Erik Price]

On Friday, August 30, 2002, at 06:54  AM, Ibraheem Umaru-Mohammed wrote:

> # match a filename that matches the following regular expression:
> # 	\d	= a single digit [0-9]
> # 	\w+	= at least one word character [a-zA-Z]
> #	\d	= a single digit [0-9]
> #	.htm	= a literal
> pattern = "\d\w+\d.htm"
> for filename in os.listdir(html_directory):
>   # if we have a match, print the matching string.
>   m = re.match(pattern, filename)
>   if m: print repr(m.group(0))

Oh, I see.  You don't have to invoke "glob" at all, you can just do a 
string test.  Great!  Thanks, Ibz.

(BTW I think that you need to escape your literal dot, otherwise it 
gets parsed as "any character" -- but then this is just an example so 
who cares.)

Since I was just learning about list comprehensions in another thread, 
I think I see where one can be used here:

      <code>
pattern = "\d\w+\d\.htm"
matches = [ m for filename in os.listdir(html_directory) if 
re.match(pattern, filename) ]
for m in matches: print repr(m.group(0))
      </code>

But I think your code is still better because it doesn't use two 
separate for loops (mine has one in the LC and another to do the 
printing).  It is just a mental exercise.



Erik

[You can't use LCs to do things like "print", right?  It just does  a 
kind of elaborate list assignment if I understand correctly.]


--
Erik Price

email: erikprice@mac.com
jabber: erikprice@jabber.org