DZone Snippets: uniq code

And then there is always CPAN ...

lucian () — Sun, 05 Feb 2006 10:06:45 GMT

// ...for those who want to keep it simple



use Uniq;

my @u_s_users=uniq sort @users;

'uniq' array

TMtm (Tony Bowden) — Mon, 30 May 2005 21:51:55 GMT

A much more idiomatic and efficient version of the 'uniq array' code at 152 is:



  # Input: @list

  # Output: @uniqed

  my %seen;

  my @uniqed = grep !$seen{$_}++, @list;

Efficient 'uniq' snippet

jmason (Justin Mason) — Wed, 13 Apr 2005 03:26:57 GMT

This snippet will quickly uniq an unsorted array; in other words, remove duplicates. (note: for large arrays, it may be more efficient to sort the array first and simply keep track of consecutive dups instead of using a hash.)



  # Input: @list

  # Output: @uniqed

  my %u = ();

  @uniqed = grep {defined} map {

      if (exists $u{$_}) { undef; } else { $u{$_}=undef;$_; }

    } @list;

  undef %u;