I was not aware of the multiple value per hash key.

Technically, there's only one: A reference to an array. Just like for AoAs. References are scalars, so they can be stored in arrays and hashes.

It will not always have the same number of elements

Which one is the cat?

I'm not sure how to use your method to output my final data to a file

It already does. The output is written to the $fh_out. I skipped over opening the file handle, but there's nothing special to it: 

my $file_out = 'data.out';
open(my $fh_out, '>', $file_out)
   or die("Unable to create output file $file_out: $!\n");

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In reply to Re^5: Help needed please: Data Manipulation in 2D Array by ikegami
in thread Help needed please: Data Manipulation in 2D Array by Syntenty

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