SPUG: Fw: Uniq in perl

[Dean Hudson]

this may make -w complain but:

@out = grep {!/^$last$/ and $last = $_} @in;

behaves like uniq; it only gets rid of adjacent duplicated lines.

dean.

On Mon, Mar 19, 2001 at 03:59:53PM -0800, Bill Alford wrote:
> Ooops, that argument was an array reference, not the full array.  Just
> change as appropriate below.
> 
> On Mon, 19 Mar 2001, Bill Alford wrote:
> 
> > All the solutions I've seen so far look good for treating the list as a
> > set (I may have missed one that didn't).  But, from the uniq man page:
> > 
> >        Discard  all  but  one  of successive identical lines from
> >        INPUT (or standard input), writing to OUTPUT (or  standard
> >        output).
> > 
> > It looks like that's what's happening below.
> > 
> > Here's what I can come up with (not tested and a little verbose, but I
> > like verbose :) :
> > 
> > sub uniq {
> >   if (! @_) {
> >     return @_;  # for the empty set case
> >   }
> >   my $last = shift;
> >   my @result = ( $last );
> >   my $cur;
> > 
> >   foreach $cur ( @_ ) {
> >     # assuming string input
> >     if ($cur ne $last) {
> >       $last = $cur;
> >       push(@result,$cur);
> >     }
> >   }
> >   return @result;
> > }
> > 
> > 
> > 
> > On Mon, 19 Mar 2001, jeff saenz wrote:
> > 
> > > What if you convert the array values to hash keys and let the hash eliminate the
> > > duplicates? Something like:
> > > 
> > > @hash{@array} = ();
> > > or maybe a map. but i think maps are inefficient.  something like that.
> > > 
> > > Richard Anderson wrote:
> > > 
> > > > Does anyone have comments for Mike?
> > > >
> > > > Richard Anderson, Ph.D.          www.unixscripts.com
> > > > Perl / Oracle / Unix                Richard.Anderson at raycosoft.com
> > > > Raycosoft, LLC                        Seattle, WA, USA
> > > > ----- Original Message -----
> > > > From: "Mike" <shivan at ici.net>
> > > > To: "Richard Anderson" <Richard.Anderson at raycosoft.com>
> > > > Sent: Friday, March 16, 2001 2:12 PM
> > > > Subject: Uniq in perl
> > > >
> > > > > This is something I had sitting around. I didn't write it. Its a subroutine
> > > > > that uniqs an array. I was just wondering if this is the best way to do it
> > > > > or if anyone has any thing better. Thanks
> > > > >
> > > > >
> > > > > ## Usage: &uniq( \@ARRAY );
> > > > > sub uniq {
> > > > > my (@uwork, @unew, $uname);
> > > > >    @uwork = @{$_[0]};
> > > > >    @uwork = sort( @uwork );
> > > > >    @unew  = ( shift @uwork );
> > > > >
> > > > >    foreach $uname ( @uwork ) {
> > > > >       @unew=( @unew, $uname) if ( $uname ne $unew[ -1 ] );
> > > > >    }
> > > > >
> > > > >    @{$_[0]}=@unew;
> > > > > }
> > > > >
> > > > > :wq
> > > > >
> > > > >
> > > >
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