Re: Reorganising a Hash for Output

[bmcatt]

Try this...

#!/usr/bin/perl -w
use strict;

my %x = ( 1 => [qw(d e f)],
      2 => [qw(a b c)],
      3 => [qw(g h i)]
      );

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

The trick (imho) is to build the "reverse" hash first and then deal with sorting / outputing that after the fact.

Btw, I'd suggest not using non-standard notation, even if it's comfortable for you. It'll (potentially) make things harder when you're trying to show other people.

[tachyon]

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;

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

cheers

tachyon

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