in reply to Re: Help needed please: Data Manipulation in 2D Array
in thread Help needed please: Data Manipulation in 2D Array

Hi, I'd like to thank you for your fast repsonse.

In regards to your solution, I've refrained from using hashes because I have elements/keys that appear more than once and I need to include them all in my final output.

For example, in file 2, the first three lines, would have the same key and different values. example:


cat1=cat2
cat1=cat9
cat1=cat10
FILE 1: dog1=bird2=cat1

So what I would have to do, is find a way to create three lines from FILE 1, push these into a new 2D array, and then join the values to the keys, so my new array will be.
index 0 - dog1=bird2=cat1=cat2
index 1 - dog1=bird2=cat1=cat9
index 2 - dog1=bird2=cat1=cat10

The reason I cannot use a hash is because in this case it would only create the first line:
index 0 - dog1=bird2=cat1=cat2
since hashes cannot have identical keys for different values.

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Re^3: Help needed please: Data Manipulation in 2D Array
by ikegami (Patriarch) on May 05, 2008 at 06:07 UTC
    No problem, just store more than one value per hash key. This is known as a HoA. 
    my %cat2s_by_cat1;

while (<$fh2>) {
   chomp;
   my ($cat1, $cat2) = split /=/;
   push @{ $cat2s_by_cat1{$cat1} }, $cat2;
}

while (<$fh1>) {
   chomp;
   my ($dog, $bird, $cat1) = split /=/;

   exists( $cat2s_by_cat1{$cat1} )
      or die;

   for my $cat2 ( @{ $cat2s_by_cat1{$cat1} } ) {
      print $fh_out (join('=', $dog, $bird, $cat1, $cat2), "\n");
   }
}

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      Thanks for your help. I was not aware of the multiple value per hash key. I forgot to mention in my original post that while file 2's data format will always have only 2 elements, FILE one will change.

      It will not always have the same number of elements, or three in this case. How can I change the second part of your code, concerning file handle 1 to account for this? And also I'm not sure how to use your method to output my final data to a file

[reply]

        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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