choroba has provided excellent suggestions. Here an option that uses a hash of arrays (HoA), where the key is the file name and its associated value is a reference to a list of frequencies:

use strict;
use warnings;

my %files;

for my $file (<*.abc>) {
    open my $fh, '<', $file or die $!;

    while (<$fh>) {
        push @{ $files{$file} }, $1 if /FREQ\s+([\d.]+)/;
    }

    close $fh;
}

print "$_  FREQ @{ $files{$_} }\n" for keys %files;

[download]

Output on files containing FREQ <val> info:

file3.abc  FREQ 27.047 400
file1.abc  FREQ 33.3 2.22
file2.abc  FREQ 12345.67

[download]

Hope this helps!

In reply to Re: print out the values from a hash by Kenosis
in thread print out the values from a hash by gibsonca

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