Somewhat late, but putting it all together, this is one solution:

use Modern::Perl;
use List::Util qw/ max sum /;
use autodie;

open my $fh1, '<', 'LookingForTheseNumbersList';
chomp ( my @wanted = <$fh1> );
close $fh1;

open my $fh2, '<', 'NumbersList';
my %found;
while ( <$fh2> ) {
  if ( /(\d+)\s+(\d+)/ and $1 ~~ @wanted ) {
    push @{ $found{$1} }, $2;
  }
}
close $fh2;

for my $k ( sort { $a <=> $b } keys %found ) {
  my @nums = @{ $found{$k} };
  say "All($k): " . join ' ', @nums;
  
  # Do some calculations, eg:
  say "Max($k): " . max @nums;
  say "Sum($k): " . sum @nums;
  say "Avg($k): " . ( sum @nums ) / @nums;
  
  say ''; # Print newline
}

[download]

Update; removed '.tmp' suffix from input file names

In reply to Re: Generating a list of numbers from other lists by Not_a_Number
in thread Generating a list of numbers from other lists by mlebel

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