Emanuel has asked for the wisdom of the Perl Monks concerning the following question:

fellow monks

I'm running into a problem issuing split invoking a regex. forgive me for the following bad regex, it's just something quick and dirty:

@lines = split(/(\d\d:\d\d:\d\d[a-zA-Z].*?[A-Z][A-Z][A-Z][A-Z]+)/,$dat
+a);

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this is working fine for $data like

00:01:00Something here bla bla blaTYPE00:02:00Something here bla bla blaANOTHERTYPE00:03:00Something here bla bla blaEVENMORETYPES

however, it (obviously) doesn't work for something like

00:01:00Something here bla bla blaType00:02:00Something here bla bla b
+laTypetoooo00:03:00Something here bla bla blaTYPETHREE

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I'm trying to build up a regex that lets split split at the digits of the next 'entry'. The outcome I need is 
0 => 00:01:00Something here bla bla blaType
1 => 00:02:00Something here bla blablaTypetoooo
2 => 00:03:00Something here bla bla blaTYPETHREE

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any help on this higly appreciated

regards
Emanuel

Replies are listed 'Best First'.
Re: split with regex
by rasta (Hermit) on Nov 01, 2002 at 14:44 UTC
    I believe this should be helpful:

    split /(?=\d\d:\d\d:\d\d)/, $data;
[reply]
[d/l]

      rasta provides an elegant solution to your problem, if you need to use split. I tend to avoid fancy things like lookahead assertions if possible, if only to simplify maintenance. Also, since I was curious, I thought I'd benchmark our two solutions.

      my $data = "00:01:00Something here bla bla blaTYPE00:02:00".
           "Something here bla bla blaANOTHERTYPE00:03:00S".
           "omething here bla bla blaEVENMORETYPES";

use Benchmark;

timethese (100000,

{ 
  withsplit => sub {
        my @lines = split /(?=\d\d:\d\d:\d\d)/, $data;
                   },

  nosplit   => sub {
        my @lines = $data =~ /(\d{2}:\d{2}:\d{2}[^\d]*)/g;
                   }
}

);

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      ...gives me...

      Benchmark: timing 100000 iterations of nosplit, withsplit...
   nosplit:  6 wallclock secs ( 7.09 usr +  0.00 sys =  7.09 CPU) @ 14
+104.37/s (n=100000)
 withsplit: 13 wallclock secs (13.85 usr +  0.00 sys = 13.85 CPU) @ 72
+20.22/s (n=100000)

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      I don't know if it's split or the lookahead that's slowing things down, but I thought you might be interested in my results anyway.

      -Bird
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[d/l]
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Re: split with regex
by Bird (Pilgrim) on Nov 01, 2002 at 15:05 UTC

    If you're trying to keep all the data you're matching, I don't know if split is the best solution. You should be fine just using a global match with capturing. Something like...

    my $data = "00:01:00Something here bla bla blaTYPE00:02:00".
           "Something here bla bla blaANOTHERTYPE00:03:00S".
           "omething here bla bla blaEVENMORETYPES";

my $moredata = "00:01:00Something here bla bla blaType00:0".
               "2:00Something here bla bla blaTypetoooo00:".
               "03:00Something here bla bla blaTYPETHREE";

my @lines = $data =~ /(\d{2}:\d{2}:\d{2}[^\d]*)/g;

my @morelines = $moredata =~ /(\d{2}:\d{2}:\d{2}[^\d]*)/g;

print "$_\n" for @lines;
print "\n";
print "$_\n" for @morelines;

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    This assumes that the text between the digits won't contain any other digits. You may need to modify the [^\d]* portion of the regex if any digits may appear in the text section. From your examples, though, this appears to do what you need.

    -Bird
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Re: split with regex
by Jaap (Curate) on Nov 01, 2002 at 14:06 UTC
    How about this: 
    split (/(\d{2}\:\d{2}\:\d{2})/, $data);

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[reply]
[d/l]
      the problem here is that it rips off the leading digits, but I do need them.. and that's my dilemma, that I can't seem to find a proper regex for this.
[reply]
        No it does not, because the regex is surrounded by (). The time is stored in a separate array element.
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