Re: [Tutor] Redux: optparse
On Sat, Dec 27, 2008 at 2:55 PM, Matt Herzog wrote:
> What I can't figure out now is how to pass a compiled regex to an optparse
> option. I'm confused ias to "option" versus "arg" when using the optparse
> module. In fact there seems to be no way to define what the arg should be;
> only options. Is the arg always implied? I have read several pages on
> optparse and am none the wiser.
You want to *retrieve* the regex from the option, not pass it to the
option. See below.
"args" is the positional arguments - any parameters that aren't
prefixed with a switch like "-x". They don't need any configuration.
> How do I fix the rx = re.compile('-x') line below so that the string I pass
> on the command line gets passed into the re.compile?
>
> #!/usr/bin/python
> import fileinput, sys, string, optparse, re
>
> #def main():
> optparser = optparse.OptionParser()
> optparser.add_option("-x", "--regx", help="regular expression")
> # take the first argument out of sys.argv and assign it to searchterm
> #searchterm, sys.argv[1:] = sys.argv[1], sys.argv[2:]
> (options, args) = optparser.parse_args()
>
> rx = re.compile('-x')
Try
rx = re.compile(options.regx)
Kent
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Re: [Tutor] Redux: optparse
> Do you want to use optparse, or get the command line arguments yourself?
> It seems the pattern string will be the first arg, will it?
Again I am confused. I assumed that optparse was the best way to pass in
arguments (such as filenames) from the command line. Like so:
./script.py -x regex *.html
> > rx = re.compile('-x')
>
> Then, if the note above is right, you have:
>
> pat_string = sys.argv[1]
> rx = re.compile(pat_string) # pattern object
>
> Is that what you wish to do?
Probablement. :) The below code does what I want:
---
#!/usr/bin/python
import fileinput, sys, string
# Take the first argument out of sys.argv and assign it to searchterm.
searchterm, sys.argv[1:] = sys.argv[1], sys.argv[2:]
for line in fileinput.input():
num_matches = line.count(searchterm)
if num_matches: # A nonzero count means there was a match.
print "found '%s' %d times in %s on line %d." % (searchterm,
num_matches, fileinput.filename(), fileinput.filelineno())
---
I wanted to use optparse instead of sys.argv. Perhaps I should study fileinput
instead. I don't understand that either.
> > for line in fileinput.input():
> > num_matches = string.count(line, rx)
> Above you are counting the number of *regex pattern* may be inside a
> string. Not the number of (sub)strings matching the pattern, which is
> probably what you intend.[ Also, you are using a deprecated function
> "count" of the string module. Use line.count(substring) instead. Anyway,
> this is probably not what you want.]
> To count the number of pattern matches, you must use the
> "matching" (lol) regex method, namely findall:
>
> result_list = rx.findall(line)
>
> > if num_matches:
> > print "found '%s' %d times in %s on line %d." % (rx, num_matches,
> > fileinput.filename(), fileinput.filelineno())
>
> Do you want to print only the last match? If not, you need to record
> matches found by the search loop into a list.
>
> > #if __name__ == '__main__':
> > #main()
>
>
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Re: [Tutor] Redux: optparse
Le samedi 27 décembre 2008 à 14:55 -0500, Matt Herzog a écrit :
> On Wed, Dec 24, 2008 at 01:12:55AM -, Alan Gauld wrote:
> >
> > "Kent Johnson" wrote
> >
> > >> for filename in os.listdir(directory):
> > >> result = re.match(s, filename)
> > >> print result
> > >
> > >You never open and read the files. You are searching for the pattern
> > >in the filename, not in the contents of the file.
> >
> > Also note that match() only searches starting at the start of the
> > string.
> >
> > Thus match will find foo at
> >
> > foobar
> >
> > but not in
> >
> > sofoo
> >
> > You usually need to use search() to find the pattern anywhere
> > within the string.
> >
> > Also look at the thread earlier this week on using listdir() and
> > the fileinput module.
>
> Hello again and thanks for the encouragement.
>
> I have been working on this problem again today and switched to the fileinput
> method. What I can't figure out now is how to pass a compiled regex to an
> optparse option. I'm confused ias to "option" versus "arg" when using the
> optparse module. In fact there seems to be no way to define what the arg
> should be; only options. Is the arg always implied? I have read several pages
> on optparse and am none the wiser.
>
> How do I fix the rx = re.compile('-x') line below so that the string I pass
> on the command line gets passed into the re.compile?
>
> #!/usr/bin/python
> import fileinput, sys, string, optparse, re
>
> #def main():
> optparser = optparse.OptionParser()
> optparser.add_option("-x", "--regx", help="regular expression")
> # take the first argument out of sys.argv and assign it to searchterm
> #searchterm, sys.argv[1:] = sys.argv[1], sys.argv[2:]
> (options, args) = optparser.parse_args()
Do you want to use optparse, or get the command line arguments yourself?
It seems the pattern string will be the first arg, will it?
> rx = re.compile('-x')
Then, if the note above is right, you have:
pat_string = sys.argv[1]
rx = re.compile(pat_string) # pattern object
Is that what you wish to do?
> for line in fileinput.input():
> num_matches = string.count(line, rx)
Above you are counting the number of *regex pattern* may be inside a
string. Not the number of (sub)strings matching the pattern, which is
probably what you intend.[ Also, you are using a deprecated function
"count" of the string module. Use line.count(substring) instead. Anyway,
this is probably not what you want.]
To count the number of pattern matches, you must use the
"matching" (lol) regex method, namely findall:
result_list = rx.findall(line)
> if num_matches:
> print "found '%s' %d times in %s on line %d." % (rx, num_matches,
> fileinput.filename(), fileinput.filelineno())
Do you want to print only the last match? If not, you need to record
matches found by the search loop into a list.
> #if __name__ == '__main__':
> #main()
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