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From: phillips@cs.ubc.ca (George Phillips)
Newsgroups: comp.lang.perl
Subject: Re: Simple perl question
Message-ID: <9212@ubc-cs.UUCP>
Date: 20 Aug 90 22:20:13 GMT
References: <24941@boulder.Colorado.EDU>
Sender: news@cs.ubc.ca
Organization: University of British Columbia, Vancouver, B.C., Canada
Lines: 45

In article <24941@boulder.Colorado.EDU> jorgy@refuge.colorado.edu (Eric R. Jorgensen) writes:
>I have input that looks like:
>
>x	1
>x	5
>x	6
>x	7
>y	25
>y	26
>
>And I would like output like:
>
>x	1,5-7
>y	25-26

Here's a script which should do it.  I'd bet Randal can manage this in
3 greps and 5 regexps or less.

#!/usr/bin/perl

while (<>) {
  ($left, $num) = split;
  $nums{$left} .= $num . " ";
}

while (($left, $num) = each %nums) {
  print "$left\t";
  @snum = sort(bynum split(' ', $num));
  $#srange = -1;
  for ($i = 0; $i <= $#snum; $i = $j) {
    for ($j = $i; $j <= $#snum && $snum[$i] == $snum[$j] + $i - $j; $j++) {}
    if ($j == $i + 1) {
      push (@srange, $snum[$i]);
    }
    else {
      push (@srange, "$snum[$i]-$snum[$j-1]");
    }
  }
  print join(',', @srange) . "\n";
}

sub bynum { $a - $b; }

--
George Phillips phillips@cs.ubc.ca {alberta,uw-beaver,uunet}!ubc-cs!phillips