SPUG: Fw: Uniq in perl

[Bill Alford]

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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> 
> 


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