Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!
I am trying using slice but I cant get it to work, any suggestions?
#!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;

my @new_order = (0, 1, 2, 3, 5, 4);

my @AoA = (
  [
    "aaa",
    "bbb",
    "ccc",
    "ddd",
    "fff",
    "eee",
  ],
  [
    "111",
    "222",
    "333",
    "444",
    "666",
    "555",
  ],
  [
    "ppp",
    "eee",
    "rrr",
    "lll",
    "kkk",
    "ooo",
  ],
);

my @new_aoa = @AoA[@new_order];
print Dumper \@new_aoa;

print "\n\n";

[download]
Thank you!

Replies are listed 'Best First'.
Re: Change elements order in an array
by choroba (Cardinal) on Oct 16, 2015 at 15:04 UTC
    It works if you change the order in the first three elements - your array doesn't have elements with indices 4 and 5 (neither 3). 
    my @new_order = (2, 1, 0);

    [download]

    BTW, that's where the undef's were coming from.

    Update: to change the order of the inner arrays, you have to slice the inner arrays: 

    my @new_aoa = map [ @$_[@new_order] ], @AoA;

    [download]
    لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ
[reply]
[d/l]
[select]
      This is what I am trying to get it:
      I asked to wrong way.
      $VAR1 = [
          [
            'aaa',
            'bbb',
            'ccc',
            'ddd',
            'eee',
            'fff'
          ],
          [
            '111',
            '222',
            '333',
            '444',
            '555',
            '666'
          ],
          [
            'ppp',
            'eee',
            'rrr',
            'lll',
            'ooo',
            'kkk'
          ],
        ];

      [download]
[reply]
[d/l]

        Please see Re: Change elements order in an array. This node has been merged with it, and this one will be reaped.

        Per part of my post in Re: Change elements order in an array, you're wanting to modify the inner arrays. This will work. Just put your original data back in. It iterates over @AoA, and for each array reference within it, slices it to the specified order, then pushes those results within a new array reference onto the @new_aoa structure. 
        my @new_order = (0, 1, 2, 3, 5, 4);

my @AoA = (
  [
      qw(1 2 3 4 5 6),
  ],
  [
      qw(a b c d e f),
  ],
);

my @new_aoa;

for (@AoA){
    push @new_aoa, [@$_[@new_order]];
}

print Dumper \@new_aoa;

        [download]
[reply]
[d/l]
[select]
Re: Change elements order in an array
by stevieb (Canon) on Oct 16, 2015 at 15:13 UTC
    What are you trying to achieve? Please provide example output. The way you're doing it now is re-ordering the top-level array only. By adding the appropriate number of elements to the top level array, you can see the results: 
    #!/usr/bin/perl
use warnings;
use strict;
use Data::Dumper;

my @new_order = (0, 1, 2, 3, 5, 4);

my @AoA = (
  [
    'zero',
  ],
  [
    'one',
  ],
  [
    'two', 
  ],
  [
    'three',
  ],
  [
    'four',
  ],
  [
    'five',
  ],
);

my @new_aoa = @AoA[@new_order];
print Dumper \@new_aoa;

__END__

$VAR1 = [
          [
            'zero'
          ],
          [
            'one'
          ],
          [
            'two'
          ],
          [
            'three'
          ],
          [
            'five'
          ],
          [
            'four'
          ]
        ];

    [download]
    If you're trying to re-sort the inner arrays, then the following should help, just replace the example data with your real structure... It iterates over @AoA, and for each array reference within it, slices it to the specified order, then pushes those results within a new array reference onto the @new_aoa structure. 
    my @new_order = (0, 1, 2, 3, 5, 4);

my @AoA = (
  [
      qw(1 2 3 4 5 6),
  ],
  [
      qw(a b c d e f),
  ],
);

my @new_aoa;

for (@AoA){
    push @new_aoa, [@$_[@new_order]];
}

print Dumper \@new_aoa;

    [download]
    -stevieb
[reply]
[d/l]
[select]
      Thats what I was missing, "A loop".
      Thank you!
[reply]

Back to Seekers of Perl Wisdom