Try... 
my %reverse_hash;
foreach my $key ( keys %hash ) {
    push @{$reverse_hash{$hash{$key}}, $key;
}

[download]

Or maybe a little clearer: 

my %reverse_hash;
while ( my ( $key, $value ) = each %hash ) {
    push @{$reverse_hash{$value}}, $key;
}

[download]


Dave

In reply to Re: mildly tricky hash question by davido
in thread mildly tricky hash question by Anonymous Monk

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