state-o-dis-array has asked for the wisdom of the Perl Monks concerning the following question:

Greetings all,
Well, some help that merlyn supplied in the past encouraged me to use map and some regex magic (magic to me, I'm sure basics to everyone else) to solve a problem, everything worked exactly as I hoped until I tried to match a numeric range - doh! can't regex a numeric range. Here's what I have, I've transformed my data and am working with it in this form: A1:123:C and I need to see if it matches any of an array of data in the form A0-7:123:C where 0-7 is a range. What I would like to know is if there is a way to match the :123:C from each expression, and if so, send the test case and match off to a sub to check for a range match of the A1 to A0-7 portion. I could do

my @array = (A0-7:123:C, B8-15:456:D);
my $check = A4:123:C;
foreach my $line(@array){
   my $subline = join(":", (split(":", $line))[1,2]);
   #not sure is that join/split thing works just consider this whateve
+r it takes to get the 123:C into $subline
   my $subcheck = #again whatever it takes to get 123:C
   if ($subcheck =~ /$subline/){
      $match = &checkRange($check, $line);
   }
}

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I'm looking for something more efficient, though. I have to test about 20-40 cases against 30-40 possible matches, and do this about 400 times, in a somewhat time sensitive environment, so effiency is key.

UPDATE: I'm not looking for the sub to determine if some number is in the range, I can do that. I'm wondering if there is a better approach than the code that I've listed?

UPDATE PART 2:
Well, I finally got as close to what I wanted to do as I think I'm going to get. I had to take care of a little tunnel vision, that I fear a shared with you in the way I presented my problem, but here is what I came up with:
my @array = (A0-7:123:C, B8-15:456:D);
my $check = A4:123:C;
my $test = join(' ', @array);
my $find = join(':', ((split(':',$check))[1,2]));
my @found = ($test =~ m/\b\w\d+\-\d+:$find\b/g);

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This way I still have my $check value, and a possible match in @found, and I can send these to a sub to check if the A4 part is in the range of the A0-7 part of the matching value. Thanks to those who were part of my problem solving process.

Replies are listed 'Best First'.
Re: matching numeric range
by jimbojones (Friar) on Feb 24, 2005 at 22:44 UTC
    Hi

    I think a hash is the answer. Assuming the second 2 elements of your data (delimited by the ':') don't involve the range, you could do something like:

    my %checks = (
               '123:C' => [ 'A[0-7]' ],
               '456:D' => [ 'B[8-9]', 'B1[0-5]' ]
             );

while ( <DATA>)
{
 chomp;
 my $check = $_;

 my $matches = 0;
 #-- get the trailing key
 my $first_part = "";
 my $key = "";
 if ( $check =~ /(\w+):(\w+:\w+)$/ )
 {
  $first_part = $1;
  $key = $2;
 }

 #-- look up key in our checks hash
 foreach my $match_pattern ( @{$checks{$key}} )
 {
  if ( $first_part =~ /$match_pattern/ )
  {
   print "Line $_ matches $match_pattern:$key\n";
   $matches = 1;
  }
 }
 print "Line $_ doesn't match\n" unless ( $matches );
}

__DATA__
A4:123:C
B8:456:D
B11:456:D
X11:456:D

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    Results 
    Line A4:123:C matches A[0-7]:123:C
Line B8:456:D matches B[8-9]:456:D
Line B11:456:D matches B1[0-5]:456:D
Line X11:456:D doesn't match

    [download]
    -j

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      I'm liking this. One question on this. Is there a simple way (one line regex substitution for example) to get from B10-15 to B1[0-5], or B120-125 to B12[0-5]? Actually, as I think about it, I may need to apply some logic to handle B18-24. Can you think of a good way to handle this one?
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        Hi

        the B10-15 example is easy: B1[0-5] (character class), as is B120-125 (B12[0-5]). As you say, logic spanning B18-24 is more difficult; that's why I broke it into 2 regexs in my post above. It was easier to match B1[8-9] or B2[0-4] than to try some regex-fu. You may be more adept with regexes than I am.

        - j

        update: escape out [ ] so they're visible.

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Re: matching numeric range
by esskar (Deacon) on Feb 24, 2005 at 22:21 UTC
    i give it a try 
    use strict;

my @check = ('A4:123:C');
my @ranges = ('A0-7:123:C', 'B8-15:456:D', 'A5-7:123:C');

foreach my $check (@check) {
   my @cp = $check =~ m!(\w)(\d+):(\d+):(\w)!;
   foreach my $range (@ranges) {
      if($range =~ m!$cp[0](\d+)\-(\d+):$cp[2]:$cp[3]!) {
         if($check[0] >= $1 and $check[0] <= $2) {
            print "$check mathes $range\n";
         }
      }
   }
}

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    HTH
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      This is probably closer to what I am looking for, thanks esskar, I have to play with the my @cp = $check =~ m!(\w)(\d+):(\d+):(\w)!; line, I've never done something like that.
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Re: matching numeric range
by Roy Johnson (Monsignor) on Feb 24, 2005 at 22:19 UTC
    I'm a little unclear about the specifics of your question, but I think the information you're looking for is in this little example program: 
    use strict; 
use warnings;

my $range_spec = 'A8-15';

# Parse the range spec:
my ($tag, $lo, $hi) = $range_spec =~ /(\D+)(\d+)-(\d+)/;

# Check the data lines
while (<DATA>) {
  chomp;
  my ($dtag, $dnum) = /(\D+)(\d+)/;
  if ($dtag eq $tag and $dnum >= $lo and $dnum <= $hi) {
    print "$_ matches $range_spec!\n";
  }
  else {
    print "Mismatch: $_\n";
  }
}
__DATA__
A1
A2
B8
B11
A11
A9
A15
A16

    [download]
    Caution: Contents may have been coded under pressure.
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Re: matching numeric range
by sh1tn (Priest) on Feb 24, 2005 at 22:43 UTC 
    use strict;

my @array = qw(A0-7:123:C B8-15:456:D);
my $check = 'A4:123:C';

_check_range(\@array, $check) and print "in range\n";


sub _check_range {
    my $arr = shift;
    my $check = shift;
    my $regex = qr{^([a-zA-Z]+)(\d+)(?:-(\d+))?:(\d+):(\w+)};

    $check =~ /$regex/ or return;

    my %check = ( 'char1', $1, 'digit1', $2, 'digit2', $4 , 'char2', $
+5 );

    for( @$arr ){
      if( /$regex/ ){
        if( $check{char1} eq $1 and $check{char2} eq $5 ){
          if( $check{digit2} == $4 ){
            $check{digit1} >= $2 and $check{digit1} <= $3 and return 1
          }
        }
      }
    }
}

    [download]


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