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Re: Regular Expression, Catching Variables

by suaveant (Parson)
on Jun 23, 2009 at 15:56 UTC ( #774074=note: print w/replies, xml ) Need Help??

in reply to Regular Expression, Catching Variables

I would suggest something like Text::CSV for this but that isn't always an option...

You're fields all seem to follow a rather basic pattern, so I would suggest that to make your life easier, you simplify how you are dealing with this... at a possible minor cost to efficiency you can just parse through the fields one by one and use a much simpler and MUCH easier to maintain regexp, like so

#!/usr/local/bin/perl use warnings; use strict; my $line = "2006-01-01,Kims,common,406,560(centrifuge,refrig.),569b,60 +7(dark room),210-211,101(ultracentrifuge),104-105(crystal growth room +s),660(centrifuge,refrig.)"; my @fields; push @fields, $1 while $line =~ /([^,(]+(?:\([^)]*\))?)/g; my $i = 1; print join(', ', map { $i++.": $_" } @fields),"\n";
Which outputs
1: 2006-01-01, 2: Kims, 3: common, 4: 406, 5: 560(centrifuge,refrig.), + 6: 569b, 7: 607(dark room), 8: 210-211, 9: 101(ultracentrifuge), 10: + 104-105(crystal growth rooms), 11: 660(centrifuge,refrig.)
Your original regexp is working just fine, but you only have 4 sets of capturing parens so you only get 4 fields... I would strongly suggest using the x modifier in big regexps like that to improve readability and also creating variables holding regexp pieces which match any fields that you can re-use the regexp for, so you only have to define a segment once.. should also add readability.

                - Ant
                - Some of my best work - (1 2 3)

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Re^2: Regular Expression, Catching Variables
by Marshall (Canon) on Jun 23, 2009 at 16:54 UTC
    Wow! Most excellent!

    Just a small addition, I think there is a missing ")" which I added below..right there at the tail-end ")/g". I also changed this to put the tokens directly into an array without the need for "while".

    #!/usr/bin/perl -w use strict; my $line = "2006-01-01,Kims,Watson,406,560(centrifuge, refrig.),569,60 +7(dark room),210-211,101(ultracentrifuge),104-105(crystal growth room +s),660(centrifuge, refrig.)"; my @tokens = $line =~ m/([^,(]+(?:\([^)]*\))?)/g; foreach my $token (@tokens) { print "$token\n"; } __END__ Prints: 2006-01-01 Kims Watson 406 560(centrifuge, refrig.) 569 607(dark room) 210-211 101(ultracentrifuge) 104-105(crystal growth rooms) 660(centrifuge, refrig.)
    Update: the only other small refinement would be to add () around the match-global to make it super clear that this is list context:
    my @tokens = ($line =~ m/([^,(]+(?:\([^)]*\))?)/g);
      You are right, when I copied it I ended up with a space there instead of a paren, and deleted it, no idea what happened, thanks.

                      - Ant
                      - Some of my best work - (1 2 3)

        I wouldn't worry about, the idea of your regex was great. This was just a typo. I have made many CTL-C CTL-V errors myself and many others! no biggie. I hope this whole thread helped the poster. Again your regex was GREAT!

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