YAL038W 1.1 2.4 4.1 YCL040W 1.1 1.6 1.8 9.11 0.0402128119838095

##</code><code>##

%hash = ('YAL038W' => [1.1, 2.4, 4.1],
         'YCL040W' => [1.1, 1.6, 1.8, 9.11, 0.0402128119838095],
         ...);

##</code><code>##

my $cur_identifier = '';
chomp $line;
foreach my $element (split /\s+/, $line) {
  if ($element !~ /\d+(?:\.\d+)?/) { # matches int or float numbers
    $cur_identifier = $element;
  }
  else {
    push @{$hash{$cur_identifier}}, $element;
  }
}