if ($key eq $thing)   {

##</code><code>##

exists $hash{$_} and push @new_array, $hash{$_} for @array;

##</code><code>##

my @new_array = map {$hash{$_}} grep {exists $hash{$_}} @array;

##</code><code>##

my @new_array = @hash{ grep {exists $hash{$_}} @array };