The trick (imho) is to build the "reverse" hash first

Wrong. What if you have duplicate values in your arrays? You will loose a whole lot of values as they can't exist as "duplicate" hash keys. Oops 

my %x = ( 1 => [qw( o o p s )],
          2 => [qw( j u s t )],
          3 => [qw( a n o t h e r )],
          4 => [qw( h a s h )],          
          5 => [qw( e r r o r )],
          6 => [qw( j u s t  a n o t h e r  p e r l  h a c k e r , )]
        );

my %rev = map { my $key=$_; map { $_=>$key} @{$x{$key}} } keys %x;
print "$_ -> $rev{$_}\n" foreach sort keys %rev;

[download]

What happened to all the values for keys 1-5?

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print

In reply to Re: Re: Reorganising a Hash for Output by tachyon
in thread Reorganising a Hash for Output by arunhorne

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