Re^6: Is there better way to delete dups in an AoH?

Roy Johnson, I still hope you're watching this thread. Your solution works great if the values of both keys in the array element are the same:

page=>'fall', chap=>'fall'

BUT, what if they are different:

my $AoH = [ { page => 'main',
              chap => 'About'},
            { page => 'main',
              chap => 'Contact'},
            { page => 'main',
              chap => 'About'},
            { page => 'sub',
              chap => 'About'},
            { page => 'sub',
              chap => 'Contact'}
          ];

my %uniq = map { ($_->{page} => 1, $_->{chap} => 1) } @$AoH;
@$AoH = map { { page => $_ , chap=>$_ } } keys %uniq;

print Dumper ($AoH);
[download]

Which prints:

$VAR1 = [
          {
            'chap' => 'Contact',
            'page' => 'Contact'
          },
          {
            'chap' => 'About',
            'page' => 'About'
          },
          {
            'chap' => 'sub',
            'page' => 'sub'
          },
          {
            'chap' => 'main',
            'page' => 'main'
          }
        ];
[download]

I want to end up with:

$VAR1 = [
          {
            'page' => 'main',
            'chap' => 'About'
          },
          {
            'page' => 'main',
            'chap' => 'Contact'
          },
          {
            'page' => 'sub',
            'chap' => 'About'
          },
          {
            'page' => 'sub',
            'chap' => 'Contact'
          }
        ];
[download]

eliminating that dupe element of:

   'page' => 'main',
   'chap' => 'About'
[download]

I've stared at it for an hour and am bewildered. Ideas? Thanks.

—Brad
"A little yeast leavens the whole dough."

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Re^7: Is there better way to delete dups in an AoH? by Roy Johnson (Monsignor) on Jun 08, 2004 at 03:32 UTC
Yes, it does call for a modified approach. What you want is a way to find each unique combination of two words, but hash keys have to be simple scalars. To uniquify a combination of two strings, we'll need a two-level hash. This relies on the fact that you know the keys of your hash (which makes it effectively a simple array). `my %uniq; for (@$AoH) { $uniq{$_->{page}}{$_->{chap}} = 1; } @$AoH = map { my $k = $_; map { {page => $k , chap=>$_} } keys %{$uniq{$k}}; } keys %uniq;` [download] The principle is the same as before: make a hash entry for each item, then find all the unique keys and rebuild the original AoH from that. The only difference is that we're going two levels deep. The PerlMonk `tr///` Advocate	[reply] [d/l]
Re^8: Is there better way to delete dups in an AoH? by bradcathey (Prior) on Jun 08, 2004 at 11:03 UTC
Magical! Roy Johnson, thanks for your excellent solution. Honestly, I'm not sure how it works, but I promise to study it." —Brad "A little yeast leavens the whole dough."	[reply]