Voilà:
%newhash = reverse do { my $hash = reverse %myhash; %hash };
To get the keys only (which are the values in the reversed hash:
@unique_keys = do { my $hash = reverse %myhash; values %hash };
update: oops, got it all wrong. It' about getting all keys where duplicate values are found.
As a single statement, formatted for readability
%myhash = (1 => 'a', 2=> 'b', 3=> 'a', 4=>'c',5 => 'b', 6 => 'a');
@k = do {
my %s;
map {
my $v=$_;
grep { $myhash{$_} eq $v} keys %myhash
} grep {$s{$_}++==1} values %myhash
};
print "$_ => $myhash{$_}\n" for @k;
__END__
6 => a
1 => a
3 => a
2 => b
5 => b
Ah well. Readability... ;-)
--shmem
_($_=" "x(1<<5)."?\n".q·/)Oo. G°\ /
/\_¯/(q /
---------------------------- \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}
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