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

I'm trying to create a 3 dimensional array

I've done two dimensionals.. (just a snipit for printing it) 

 @nine = (0,1,2,3,4,5,6,7,8);
foreach $row (@nine) {
    foreach $column (@nine) {
        print "$matrix[$row][$column]";
    }
    print "\n";
}

[download]

But the three dimensionals seem beyond me. This piece is supposed to pull items off of some input $_ one buy one and push them one by one to a different array (thats inside of an array called column, thats inside of an array called row)

I had the two dimensional version pulling one by one off of $_ and assigning them to the elements in $matrix$row$column and that worked fine.

 foreach $row(@nine) {
    foreach $column(@nine) {
        s/\d//;
        push(@matrix[$row][$column], $&);
        }
}

[download]

Basically I want a 9 by 9 matrix that hold an array instead of just a scaler.

I can implement the array I want well enough the long way.. But as you see in my horrible code, I don't have the knowledge required to reference it.

Oh please, mighty perl monks, lend me your knowledge so that I might continue on my perl journey

Replies are listed 'Best First'.
Re: Multi-dimensional arrays...
by ikegami (Patriarch) on May 31, 2009 at 18:17 UTC

    Basically I want a 9 by 9 matrix that hold an array instead of just a scaler.

    for my $row (0..8) {
   for my $col (0..8) {
      my @record = ...;
      $data[$row][$col] = \@record;
   }
}

    [download]

    If the above "..." is built using a loop, you can avoid the intermediary variable @record: 

    for my $row (0..8) {
   for my $col (0..8) {
      for my $x (...) {
         push @{ $data[$row][$col] }, $x;
      }
   }
}

    [download]
[reply]
[d/l]
[select]

      Wouldn't this solution make all elements of the double array point to the same reference, which means the same array?

      What if they need to each have there own separate array?

[reply]

        No, the my @record = ...; inside the inner loop creates a new lexically scoped array each iteration. Consider the following code.

        $ perl -Mstrict -wle '
> my @arr;
> foreach my $iter ( 1 .. 3 )
> {
>     my @rec = map { $_ * $iter } ( 1, 2, 3 );
>     push @arr, \ @rec;
> }
> print qq{$_: @$_} for @arr;'
ARRAY(0x22aa8): 1 2 3
ARRAY(0x22b14): 2 4 6
ARRAY(0x22b80): 3 6 9
$

        [download]

        Note how the references are different for each element of @arr and the contents reflect the value of $iter each time through the loop.

        I hope this is helpful.

        Cheers,

        JohnGG

[reply]
[d/l]
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Re: Multi-dimensional arrays...
by Anonymous Monk on May 31, 2009 at 18:15 UTC
[reply]
Re: Multi-dimensional arrays...
by locked_user sundialsvc4 (Abbot) on May 31, 2009 at 22:06 UTC
    When you are dealing with "many dimensional arrays," sometimes a better way to visualize it, and to implement it, is by a general container-class having a list (an "n-tuple") as its key ... This can be obtained readily, and it can make your code much easier to build and to maintain.
Re: Multi-dimensional arrays...
by hda (Chaplain) on Jun 01, 2009 at 05:40 UTC
[reply]

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