I have a two-layer hash, i.e.

$hash{ $key1 }{ $key2 } = $value;

I'd like to convert it into an array of hashes from the second layer. This is for JSON-style data, an "array of records". i.e.

@Array( \$hash{$key1}, ...)

My first attempt was writing nested foreach loops but I was creating @Array from scratch, with new anonymous hash references, so I was actually creating new copies of all the data in memory.

foreach $key1 (keys %hash) {
    foreach $key2 (keys %{$hash{$key1}}) {
        push(@Array, { key2_ => $hash{$key1}{$key2} });
}

[download]

How can I do this in code without having to create new copies of all the data? This hash is really big so I'm trying to be efficient. It seems like I should be able to just grab references to all the subkeys.

Something like this:

foreach $key1 (keys %hash) {
    push(@Array, \%{ $hash{$key1} });
}

[download]

I was trying to figure out how to do it with a map but couldn't seem to figure it out.

In reply to Convert hash of hashes into array of hahes by Anonymous Monk

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