gri6507 has asked for the wisdom of the Perl Monks concerning the following question:

Fellow monks,

I know this should be simple, but I am tired and am not seeing the problem. Here's my code:

use strict;
use warnings;
use Data::Dumper;

my @trainset = ();
while (my $pattern = <DATA>) {
 chomp $pattern;
 next if ($pattern =~ /#/);
 my ($inputs,$outputs) = split(/=>/,$pattern);
 my @inputs = split(/,/,$inputs);
 my @outputs = split(/,/,$outputs);
 $trainset[scalar(@trainset)] = \@inputs;
 $trainset[scalar(@trainset)] = \@outputs;
}
print Dumper(\@trainset);

my @set = (
           [0,0] => [0],
           [0,1] => [1],
          );
print Dumper(\@set);

__DATA__
0,0=>0
0,1=>1
#not used

[download]

The two arrays should be the same, but the output of Data::Dumper on the two arrays is different (when read in from a handle, the values in the arrays are scalars instead of numbers) and I think it's causing me problems further on. What am I doing wrong?

Thanks a bundle.

Replies are listed 'Best First'.
Re: Array definition error
by sasikumar (Monk) on Apr 15, 2005 at 15:32 UTC
    Hi,
    If i had understood the question right. Perl has no clue in finding the datatype of ur @outputs and @inputs. Give it some clue to find it out. It would do what u were asking for.
    Try this 
    use strict;
use warnings;
use Data::Dumper;

my @trainset = ();
while (my $pattern = <DATA>) {
 chomp $pattern;
  next if $pattern =~ /^\s*$/;
 next if ($pattern =~ /#/);
 my ($inputs,$outputs) = split(/=>/,$pattern);
 my @inputs = split(/,/,$inputs);
 my @outputs = split(/,/,$outputs);
 for(my $i=0;$i<@outputs;$i++)
 {
     $outputs[$i]=$outputs[$i]+1-1;
 }
 for(my $i=0;$i<@inputs;$i++)
 {
     $inputs[$i]=$inputs[$i]+1-1;
 }
 $trainset[scalar(@trainset)] = \@inputs;
 $trainset[scalar(@trainset)] = \@outputs;
}
print Dumper(\@trainset);

my @set = (
           [0,0] => [0],
           [0,1] => [1],
          );
print Dumper(\@set);

__DATA__
0,0=>0
0,1=>1
#not used

    [download]
    Thanks
    SasiKumar
[reply]
[d/l]
      That works... or...(if this is even a necessary step) 
      use strict;
use warnings;
use Data::Dumper;

my @trainset = ();
while (my $pattern = <DATA>) {
 chomp $pattern;
 next if ($pattern =~ /#/);
 my ($inputs,$outputs) = split(/=>/,$pattern);
 my @inputs = split(/,/,$inputs);
 my @outputs = split(/,/,$outputs);

 $_+0 foreach @outputs;  # added
 $_+0 foreach @inputs;   # added

 $trainset[scalar(@trainset)] = \@inputs;
 $trainset[scalar(@trainset)] = \@outputs;
}
print Dumper(\@trainset);

my @set = (
           [0,0] => [0],
           [0,1] => [1],
          );
print Dumper(\@set);

__DATA__
0,0=>0
0,1=>1
#not used

      [download]
      --------------
      "But what of all those sweet words you spoke in private?"
      "Oh that's just what we call pillow talk, baby, that's all."
[reply]
[d/l]
Re: Array definition error
by RazorbladeBidet (Friar) on Apr 15, 2005 at 15:21 UTC
    What are you trying to do? 
    $trainset[scalar(@trainset)] = \@inputs;
$trainset[scalar(@trainset)] = \@outputs;

    [download]
    Is going to set the value to be \@outputs only (it will override).

    So you should get 0 and 1 (the values of the outputs only) as your array elements.

    Ok, nevermind, I'm thoroughly confused :)

    I tested this and found the outputs to be the same except that the @trainset values are treated as strings. 

    $VAR1 = [
          [
            '0',
            '0'
          ],
          [
            '0'
          ],
          [
            '0',
            '1'
          ],
          [
            '1'
          ]
        ];
$VAR1 = [
          [
            0,
            0
          ],
          [
            0
          ],
          [
            0,
            1
          ],
          [
            1
          ]
        ];

    [download]
    --------------
    "But what of all those sweet words you spoke in private?"
    "Oh that's just what we call pillow talk, baby, that's all."
[reply]
[d/l]
[select]
      Actually that's not true. The line $trainset[scalar(@trainset)] = \@inputs; will increase the side of the @trainset array so that when $trainset[scalar(@trainset)] = \@outputs; is called, scalar(@trainset) will be one larger and therefore not overwrite the original data. This is akin to a push.
[reply]
[d/l]
[select]

        You statment is true. However, I'd like to ask why you are not simply using push? Does this method offer some benifit that I do not see? If so, please enlighten me.

        A truely compassionate attitude towards other does not change, even if they behave negatively or hurt you

        —His Holiness, The Dalai Lama

[reply]
Re: Array definition error
by gri6507 (Deacon) on Apr 15, 2005 at 15:21 UTC
    I truly am tired. I found out what was causing my problems later on in my program. (The rest of my program uses compiles XS code and I was passing incorrect parameters to it).

    However, for purely academic reasons, my question still remains: how are the two arrays different?

[reply]
      The one you're building has strings as its fundamental elements. The other has numbers.
      Caution: Contents may have been coded under pressure.
[reply]
Re: Array definition error
by sh1tn (Priest) on Apr 15, 2005 at 15:22 UTC
    It's because of the empty lines: 
    ...
while (my $pattern = <DATA>) {
 next if $pattern =~ /^\s*$/;
...

    [download]


[reply]
[d/l]
      what empty lines? The __DATA__ only has three lines and they are all non-empty.
[reply]

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