Date: Fri, 05 Oct 2001 14:22:43 +0100
From: Jasper McCrea <jasper@guideguide.com>
Subject: Re: Skipping following lines if the same
Message-Id: <3BBDB423.CFC98433@guideguide.com>

Laird wrote:
> 
> Hi everyone,
> 
> I've got this array
> 
> aaa
> aaa
> bbbbb
> cccc
> cccc
> c
> ddd
> ddd
> fff
> fff
> fff
> ffff
> ffff
> 
> and would like to transform it into this
> 
> aaa
> bbbbb
> cccc
> c
> ddd
> fff
> ffff
> 
> skipping following lines if the same.
> But only following lines.
> 
> I tried this but it doesn't work.
> 
> #!/usr/bin/perl
>      open (IN,data);
>      @a=<IN>;
>      for (@a){
>      $i++;
>      chomp $a[$i];
>      print "$a[$i]\n" if /$a[$i]/ ne /$a[$i+1]/
>      }
> 
> Cordially
> Ken

you could use:

my $last = '';
@a = map { $last eq $_ ? () : ($last = $_) } @a;

unfortunately, if you have umpteen empty elements at the start, these
will be included (not much of a problem if reading from a file). And
it's only useful if you've slurped the whole file first.

Jasper
-- 
      split//,'019617511192'.
      '17011111610114101114'.
      '21011141011840799901'.
            '17101174';
            foreach(0..         # my
            $#_){$_[$_          # signature is too
            ++]^=$_[$_          # bignature
            --]^=$_[$_
]^=$_[++    $_]if!($_%
2)}$g.=$_  ,chr($g)=~
 /(\w)/&&($o.=$1and
   $g='')foreach@_;
      print"$o\n"