On 06/28/2010 07:29 PM, Ken D'Ambrosio wrote:
> Hi, all. I've got a file which, in turn, contains a couple thousand
> filenames. I'm writing a web front-end, and I want to return all the
> filenames that match a user-input value. In Perl, this would be something
> like,
>
> if (/$value/){print "$_ matches\n";}
>
> But trying to put a variable into regex in Python is challenging me --
> and, indeed, I've seen a bit of scorn cast upon those who would do so in
> my Google searches ("You come from Perl, don't you?").
>
> Here's what I've got (in ugly, prototype-type code):
>
> file=open('/tmp/event_logs_listing.txt' 'r') # List of filenames
> seek = form["serial"].value # Value from web form
> for line in file:
> match = re.search((seek)",(.*),(.*)", line) # Stuck here
without re:
for line in file:
if line.startswith(seek): # or: if seek in line...
# do stuff
with re and classic string formatting:
for line in file:
# or use re.match to look only at the beginning of the line
match = re.search('(%s),(.*),(.*)' % seek, line)
if match:
#use match.group(n) for further processing
You could also concatenate strings to get the regexp, as in:
'('+seek+'),(.*),(.*)'
Note that while using re is perl way to do strings, Python has a bunch
of string methods that are often a better choice, such as str.startswith
or the ("xyz" in "vwxyz!") syntax.
if you just want to get the matching lines, you could use list
comprehension:
matching = [ln for ln in file if ln.startswith(seek)]
Just to present some of the ways you can do this in Python. I hope
you're enjoying the language.
-- Thomas
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