use strict;
use warnings;
use Data::Dumper;

my @prizes =
  (
    {
    'Timestamp' => '2005-11-07 11:18:01',
    'WinnerId' => '2026',
    'lineid' => '2026',
    },
    {
    'Timestamp' => '2005-01-07 11:18:01',
    'WinnerId' => '2001',
    'lineid' => '2001',
    },
    {
    'Timestamp' => '2005-05-07 11:18:01',
    'WinnerId' => '2015',
    'lineid' => '2015',
    },
  );
    
my %month =
  (
  '01' => 'January',
  '02' => 'February',
  '03' => 'March',
  '04' => 'April',
  '05' => 'May',
  '06' => 'June',
  '07' => 'July',
  '08' => 'August',
  '09' => 'September',
  '10' => 'October',
  '11' => 'November',
  '12' => 'December',
  );

my @mapped_prizes = map {[$month{(split (/-/, $_->{'Timestamp'}))[1]} => $_]} @prizes;

print Dumper (\@mapped_prizes);