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

Two part question:

PartA: 

@value = {$hoh{$newcount}{'individual'}};
print "@value \n";

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This should reference values generated in the HoH below.
...
    {
        $HoH{$counter} =
    {
        individual  => [ @newind ],
        chromasome1 => [ @newchroma ],
        chromasome2 => [ @newchromb ],
    };
    }
...

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However, it gives me HASH(0x180bef4) rather then the list I want, and throws this warning: Odd number of elements in anonymous hash at (I can't follow previous discussion they are greek to me)...I figure the answer is something simple, I just can't figure out what the simple thing is.

PartB: Once this works can I then modify the @value, and replace @newchroma with @value? Sounds simple to say...but I am not seeing how this is easy to do. Thanks monks...

Replies are listed 'Best First'.
Re: Why is this not what I think it is...
by GrandFather (Saint) on Nov 06, 2007 at 01:32 UTC

    use strict; use warnings;. You use %hoh in the first code sample and %HoH in the second.

    {$HoH{1}{'individual'}} tries to generate an anonymous hash but only provides one element - a hash requires pairs of elements. Very likely you intended my @value = @{$HoH{$counter}{'individual'}}; to cast the array reference to an array.

    Possibly the overall code you are looking for is something like:

    use strict;
use warnings;

my %HoH;
my @newind = (1 .. 3);
my @newchroma = (4 .. 6);
my @newchromb = (7 .. 9);

$HoH{1} =
    {
        individual  => [@newind],
        chromasome1 => [@newchroma],
        chromasome2 => [@newchromb],
    };

my @value = @{$HoH{1}{'individual'}};
print "@value \n";

$value[0] = 42;
$HoH{1}{'chromasome1'} = [@value];
print "@{$HoH{1}{'chromasome1'}}\n";

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    Prints:

    1 2 3 
42 2 3

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    Perl is environmentally friendly - it saves trees
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Re: Why is this not what I think it is...
by graff (Chancellor) on Nov 06, 2007 at 03:49 UTC
    You're pretty close. I think you just forgot a necessary "@" sigil in the assignment to @value. Try it like this: 
    @value = @{$hoh{$newcount}{'individual'}};

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    Here's a little one-liner cook-book example to demonstrate the concept: 
    perl -MData::Dumper -e '%h=(one=>{a=>[1,2,3],b=>[4,5,6]},two=>{b=>[5,6
+,7],c=>[7,8,9]});
 print Dumper(\%h); @a=@{$h{one}{a}}; print Dumper(\@a)'

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    When I run that, I get: 
    $VAR1 = {
          'one' => {
                     'a' => [
                              1,
                              2,
                              3
                            ],
                     'b' => [
                              4,
                              5,
                              6
                            ]
                   },
          'two' => {
                     'c' => [
                              7,
                              8,
                              9
                            ],
                     'b' => [
                              5,
                              6,
                              7
                            ]
                   }
        };
$VAR1 = [
          1,
          2,
          3
        ];

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Re: Why is this not what I think it is...
by BioNrd (Monk) on Nov 06, 2007 at 14:24 UTC
    Thanks for the help. It is a learning process. I am surprised I have gotten this far (a lot farther with the help). Speaks wonders for the ease of perl as a language that someone with no experience can pick it up in a months time.
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